###2001.03.10: cikkek letoltese, megkezdodott. ###2001.10.15: A 2001-es évbeli cikk is letöltődött. (L. első hivatkozás) FN ISI Export Format VR 1.0 Author(s): Urbaniak M; Stobiecki F; Lucinski T; Szymanski B Title: Annealing effects on Py/Cu GMR multilayer films with limited number of sublayers Source: PHYSICA STATUS SOLIDI A-APPLIED RESEARCH 2001, Vol 186, Iss 3, pp 423-435 Abstract: The influence of annealing on giant magnetoresistance (GMR) effect and magnetization reversal processes has been investigated in Py/Cu (Py = Ni83Fe17) sputter-deposited multilayers (MLs) with a limited number of magnetic sublayers (N less than or equal to 6) and equal sublayer thicknesses both for Py and Cu (t(Cu) = 2 nm, t(Py) = 2 nm). Based on the magnetization and magnetoresistance measurements it has been shown that the magnetic behavior of such MLs is strongly influenced by annealing driven disruption of magnetic layers (lateral decoupling) and nonmagnetic layers (magnetic bridging between Py layers). A comparison of experimental hysteresis curves with model dependences indicates that annealing causes a change of the magnetization reversal from a local to an absolute energy minimum mode leading to quasi-two-state magnetoresistance characteristics. Times Cited: 0 Source item page count: 13 Publication Date: AUG 16 IDS No.: 469YW 29-char source abbrev: PHYS STATUS SOLIDI A-APPL RES #Letoltve[2001.03.10] PT Journal AU Yan, SS Grunberg, P Mei, M TI Magnetic phase diagrams of the trilayers with the noncollinear coupling in the form of the proximity magnetism model SO JOURNAL OF APPLIED PHYSICS AB The magnetic phase diagrams of Fe/Mn/Fe trilayers with the noncollinear interlayer coupling in the form of the proximity magnetism model were theoretically studied. The C+-C- phase diagram in the remanent magnetization state predicts very rich spin configurations. The H-C+ and H-C- phase diagrams show that the spin configurations of Fe/Mn/Fe trilayers depend strongly on the external magnetic field, the anisotropy of Fe layers, and the coupling coefficients C+ and C-. Our experimental results of noncollinear spin configurations of Fe/Mn/Fe trilayers strongly support the magnetic phase diagrams based on the proximity magnetism model. (C) 2000 American Institute of Physics. [S0021-8979(00)00914-2]. TC 1 BP 983 EP 987 PG 5 JI J. Appl. Phys. PY 2000 PD JUL 15 VL 88 IS 2 GA 329DA J9 J APPL PHYS UT ISI:000087889800060 ER #Most nincs letoltve, esetleg kesobb... PT Journal AU Dieny, B Li, M Liao, SH Horng, C Ju, K TI Quantitative interpretation of the magnetoresistive response (amplitude and shape) of spin valves with synthetic antiferromagnetic pinned layers SO JOURNAL OF APPLIED PHYSICS AB We present an analytical calculation of the shape of the magnetoresistive response of spin-valve structures with synthetic antiferromagnetic pinned layer, i.e., of the form buffer/ferromagnet1/Cu/ferromagnet2/Ru/ferromagnet3/antiferroma gnet. The magnetization reversal in the three magnetic layers is assumed to occur via coherent rotation. An analytical expression of the whole hysteresis loop is given as a function of the characteristic parameters of the system (coupling strength through the Ru spacer, ferromagnet3/antiferromagnet pinning energy). We also extended a code based on the Boltzmann equation of transport to calculate the giant magnetoresistance (GMR) amplitude in these structures from the microscopic transport parameters. In order to explain the relatively high GMR amplitude experimentally observed in such spin valves, it is shown that some degree of specular reflection must be introduced at the ferromagnet2/Ru interface. Good agreement with both the shape and amplitude of the experimental magnetoresistance curves can be obtained. (C) 2000 American Institute of Physics. [S0021-8979(00)01907-1]. TC 1 BP 3415 EP 3420 PG 6 JI J. Appl. Phys. PY 2000 PD APR 1 VL 87 IS 7 GA 293WN J9 J APPL PHYS UT ISI:000085878100038 ER #Letoltve, kinyomtatva [2001.03.10] PT Journal AU Yanagihara, H Kita, E Salamon, MB TI Aperiodical oscillation of interlayer coupling in epitaxial Co/Ir(001) superlattices SO PHYSICAL REVIEW B AB High quality epitaxial cobalt-iridium superlattices were successfully grown on MgO(001) substrates via molecular-beam epitaxy and were found to exhibit anomalous oscillatory interlayer exchange coupling with a strong coupling constant. The aperiodical antiferromagnetic (AF) peaks appear at Ir layer thicknesses of 5 Angstrom, 15 Angstrom, and 33 Angstrom. Maximum magnetoresistance (MR) ratios of approximate to 1.1% are obtained and are almost the same for the first and the second AF peaks. The interlayer coupling corresponding to the first AF peak is so strong that the magnetization did not saturate even in an applied field up to 90 kOe. The estimated value of the interlayer exchange constant by MR curves at room temperature is more than 2.2 erg/cm(2) close to the first AF peak. A distinction of the in-plane magnetization process between [100] and [110] directions is observed and the easy axis of magnetization is found to be along the [110] axis in plane. The aperiodic oscillations are thought to indicate multiperiodicity of the interlayer exchange constants. [S0163- 1829(99)01742-7]. TC 2 BP 12957 EP 12962 PG 6 JI Phys. Rev. B PY 1999 PD NOV 1 VL 60 IS 18 GA 257CV J9 PHYS REV B UT ISI:000083765400062 ER #Nincs on-line hozzaferes -> konyvtarban, egyetemen megnezni! PT Journal AU Zhou, L Kawazoe, Y TI Unified spin-wave theory for quantum spin systems with single- ion anisotropies SO JOURNAL OF PHYSICS A-MATHEMATICAL AND GENERAL AB By introducing a new spin-Bose transformation which incorporates the single-site spin-states mixing effect self- consistently, we establish a unified spin-wave approach, applicable to an arbitrary spin-number case and general spin configurations, for quantum spin systems with single-ion anisotropies. The conventional Holstein-Primakoff (HP) method completely fails for such systems with easy-plane anisotropy and sometimes fails for those with easy-axis anisotropy, while these difficulties have been overcome successfully by the new method. In some limiting cases, the present method recovers the results of old theories which are valid in such cases. Applications to magnetic multilayers show that the new method is useful to remove the unphysical instability predicted by the conventional HP method. TC 0 BP 6687 EP 6704 PG 18 JI J. Phys. A-Math. Gen. PY 1999 PD SEP 24 VL 32 IS 38 GA 241BK J9 J PHYS-A-MATH GEN UT ISI:000082862000010 ER #Mar megvan PT Journal AU Yu, MH Zhang, ZD Zhao, T TI Spin configurations and magnetization reversal processes in ultrathin cubic ferromagnetic films with in-plane uniaxial anisotropy SO JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS AB Based on a phenomenological model, spin structures either in the absence or in the presence of an external magnetic field have been studied for ultrathin cubic ferromagnetic films with an in-plane uniaxial anisotropy. Phase diagrams of the spin configurations in the absence of the magnetic field and of different magnetization reversal processes have been given. The magnetization reversal processes in the ultrathin cubic ferromagnetic films have been found to depend sensitively on the competition among the energies of in-plane uniaxial and cubic anisotropies and of the domain wall pinning. (C) 1999 Elsevier Science B.V. All rights reserved. TC 0 BP 327 EP 335 PG 9 JI J. Magn. Magn. Mater. PY 1999 PD MAY VL 195 IS 2 GA 196HH J9 J MAGN MAGN MATER UT ISI:000080302600011 ER #Letoltve [2001.03.10] PT Journal AU Yu, MH Zhang, ZD TI Spin configurations in the absence of an external magnetic field in a magnetic bilayer with in-plane cubic or uniaxial anisotropies SO JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS AB The spin configurations in the absence of an external magnetic field have been systematically investigated for a magnetic bilayer system consisting of two ferromagnetic layers separated by a non-magnetic layer with interlayer exchange coupling. Based on a phenomenological model, the conditions for the existence of collinear and non-collinear spin structures were derived for three kinds of magnetic bilayers with different combinations of in-plane cubic and uniaxial anisotropies for the two ferromagnetic layers. The phase diagrams of the spin configurations at zero field were drawn, taking into account the lowest-order anisotropy parameters of both the ferromagnetic layers. The values of the canting angle have been derived analytically and then numerically plotted. (C) 1999 Elsevier Science B.V. All rights reserved. TC 0 BP 514 EP 519 PG 6 JI J. Magn. Magn. Mater. PY 1999 PD MAY VL 195 IS 2 GA 196HH J9 J MAGN MAGN MATER UT ISI:000080302600033 ER #Most nincs letoltve, nincs is meg a konyvtarban, talan kesobb meg erdekese #lehet -> akkor utanajarni, hogy hol lehet beszerezni. PT Journal AU Kurkin, MI Khusainov, DZ TI Effect of noncrystallographic magnetic anisotropy on magnetization reversal in multilayer magnetic films SO PHYSICS OF THE SOLID STATE AB A study has been carried out of the magnetization of a layered system consisting of two exchange-coupled easy-axis ferromagnetic layers separated by a nonmagnetic spacer and having mutually perpendicular anisotropy axes. It is shown that the magnetization of such a system can undergo stepwise decrease with increasing magnetic field. The field dependence of the magnetization has a bifurcation point. The magnetization orientation can exhibit jumps in excess of 90 degrees depending on the angle of magnetic-field orientation. (C) 1999 American Institute of Physics. [S1063-7834(99)02104-8]. TC 0 BP 595 EP 598 PG 4 JI Phys. Solid State PY 1999 PD APR VL 41 IS 4 GA 192JQ J9 PHYS SOLID STATE UT ISI:000080075600021 ER #Nincs meg, nics letoltve. PT Journal AU Ma, P Anderson, GW Norton, PR TI An in-situ study of structure and magnetic properties of Fe films on the sulphur passivated Ge(100) surface at 150 degrees C SO SURFACE SCIENCE AB Ultra-thin Fe films have been grown on the sulphur passivated Ge(100) surface at 150 degrees C. The growth, structure and the magnetic properties of the thin films were studied with LEED, AES, angle resolved AES and in-situ magnetooptical Kerr effect measurements. For the first five monolayers of Fe, no long- range order was observed. However, angle resolved AES data suggest that local order occurs with a small fraction of the Fe atoms adsorbed on bcc sites. For thicker Fe films, the growth becomes ordered. A comparison of the present study and with a previous study of the growth of Fe on sputter cleaned Ge(100) (2 x 1) surface, shows that sulphur passivation effectively prevents Fe-Ge intermixing. During the Fe deposition process, most of the sulphur atoms migrate to the growing surface, thus acting as surfactants. The presence of sulphur at the surface also affects the growth and magnetic properties of the thin films. (C) 1999 Elsevier Science B.V. All rights reserved. TC 1 BP 134 EP 141 PG 8 JI Surf. Sci. PY 1999 PD JAN 20 VL 420 IS 2-3 GA 166FU J9 SURFACE SCI UT ISI:000078566200005 ER #Permalloy -> erdekes lehet, hatha jobban no... #Letolvte 2001.03.10, kinyomtatva PT Journal AU Urbaniak, M Lucinski, T Stobiecki, F TI High sensitivity GMR with small hysteresis in Ni-Fe/Cu multilayers SO JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS AB Giant magnetoresistance (GMR) effect and magnetisation reversal processes have been investigated in Py/Cu(Py = Ni83Fe17, permalloy) multilayers (Mls) obtained by face-to-face sputtering method. The investigated films had constant sublayer thicknesses both for Py and Cu (d(Cu) = 2 nm, d(Py) = 2 nm) and various numbers of ferromagnetic sublayers. It has been shown that for such Mis a high held sensitivity of GMR effect (S approximate to 0.4%/Oe) and negligible hysteresis can be obtained for a low number of Py layers. (C) 1998 Elsevier Science B.V. All rights reserved. TC 2 BP 187 EP 192 PG 6 JI J. Magn. Magn. Mater. PY 1998 PD DEC VL 190 IS 3 GA 144DN J9 J MAGN MAGN MATER UT ISI:000077298700006 ER #Mar megvan. PT Journal AU Tolinski, T Baszynski, J TI Anomalous coercivity in hysteresis loops of antiferromagnetically coupled Fe/Ag/Fe trilayers on MgO(001) substrates SO PHYSICA STATUS SOLIDI A-APPLIED RESEARCH AB A numerical simulation of the demagnetization process (hysteresis loop) is performed in order to evaluate the bilinear and biquadratic coupling in the MgO/[Fe/Ag/Fe]/Ag trilayer. The proposed approach is intermediate between the model assuming that the system always reaches the Global Energy Minimum (GEM) and the model considering the situation when the system follows the Local Energy Minimum (LEM). The intermediate approach is realized by defining the energy barrier parameter E-b determining the transition between the local energy minima. The value of E-b can be obtained using reference (uncoupled) samples. The numerical algorithm applied to the GEM, LEM and the intermediate model is described. The bilinear J(1) and biquadratic J(2) coupling parameters are determined from the ferromagnetic resonance and hysteresis loop measurements. TC 0 BP 139 EP 143 PG 5 JI Phys. Status Solidi A-Appl. Res. PY 1998 PD SEP 16 VL 169 IS 1 GA 127KZ J9 PHYS STATUS SOLIDI A-APPL RES UT ISI:000076351300022 ER #Nem erdekes annyira, nincs letoltve PT Journal AU Michel, RP Chaiken, A Wang, CT Johnson, LE TI Exchange anisotropy in epitaxial and polycrystalline NiO/NiFe bilayers SO PHYSICAL REVIEW B AB (001)-oriented NiO/NiFe bilayers were grown on single crystal MgO (001) substrates by ion beam sputtering in order to determine the effect that the crystalline orientation of the NiO antiferromagnetic layer has on the magnetization curve of the NiFe ferromagnetic layer. The simplest model predicts no exchange anisotropy for the (001)-oriented NiO surface, which in its bulk termination is magnetically compensated. Nonetheless exchange anisotropy is present in the epitaxial films, although it is approximately half as large as in polycrystalline films that were grown simultaneously. The surface anisotropy in the epitaxial films is found to contain cubic and unidirectional components, while that in the polycrystalline film is best described by a uniaxial plus unidirectional anisotropy. Experiments indicate that differences in exchange field and coercivity between polycrystalline and epitaxial NiFe/NiO bilayers couples arise due to variations in induced surface anisotropy. Implications of these observations for models of induced exchange anisotropy in NiO/NiFe bilayer couples will be discussed. TC 9 BP 8566 EP 8573 PG 8 JI Phys. Rev. B PY 1998 PD OCT 1 VL 58 IS 13 GA 125HU J9 PHYS REV B UT ISI:000076232100067 ER #Majd leuvenben lemasolni, hatha erdekes lehet... PT Journal AU Bruynseraede, C Lauhoff, G Bland, JAC Strijkers, G De Boeck, J Borghs, G TI Strong anti-ferromagnetic coupling in tau MnAl/Co perpendicular magnetic superlattices on GaAs. SO IEEE TRANSACTIONS ON MAGNETICS AB This paper reports on the-structural and magnetic properties of tau MnAl/Co superlattices epitaxially grown on AlAs/GaAs by Molecular Beam Epitaxy. In tau MnAl/Co superlattices with Co layer thickness < 8 Angstrom, a strong anti-ferromagnetic coupling between the ferromagnetic tau MnAl and Co layers is found, as well as the presence of a large perpendicular magnetic anisotropy in both constituent layers, resulting in an unusually abrupt spin reversal at high fields. When increasing the Co layer thickness, the shape anisotropy in the Co layers dominates this AF coupling and the constituent layers display different magnetization directions: perpendicular (tau MnAl) and parallel (Co) to the growth plane. TC 0 BP 861 EP 863 PG 3 JI IEEE Trans. Magn. PY 1998 PD JUL VL 34 IS 4 PN 1 GA 101CP J9 IEEE TRANS MAGN UT ISI:000074852300013 ER #Mar megvan PT Journal AU Chesman, C Lucena, MA de Moura, MC Azevedo, A de Aguiar, FM Rezende, SM Parkin, SSP TI Magnetic trilayers with bilinear and biquadratic exchange couplings: Criteria for the measurement of J(1) and J(2) SO PHYSICAL REVIEW B AB We have analytically calculated phase boundaries of magnetic trilayers with bilinear and biquadradic exchange couplings in order to investigate possible phase transitions in these systems as the external magnetic field, applied either along an easy or a hard magnetization axis, is varied. A simple scheme is obtained for both antiferromagnetic and ferromagnetic couplings that is shown to be consistent with magnetization curves previously measured in different systems. In addition, experimental data regarding static and dynamic responses in sputtered (100) Fe(40 Angstrom)/Cr(t(Cr))/Fe(40 Angstrom) are reported for the Cr thickness in the range 15 Angstrom < t(Cr) < 35 Angstrom. As a result, our model calculations indicate that the bilinear and biquadratic exchange coupling constants, J(1) and J(2), cannot be accurately determined from a fit to the experimental data when the ratio J(2)/\J(1)\ > 1, and if only the main magnetization axes are considered. [S0163- 1829(98)02725-8]. TC 4 BP 101 EP 104 PG 4 JI Phys. Rev. B PY 1998 PD JUL 1 VL 58 IS 1 GA ZY633 J9 PHYS REV B UT ISI:000074643200027 ER #Letoltve [2001.03.10.] PT Journal AU Poulopoulos, P Bovensiepen, U Farle, M Baberschke, K TI Temperature-dependent crossover from ferro- to antiferromagnetic interlayer alignment due to magnetic anisotropy energy SO PHYSICAL REVIEW B AB The temperature dependence of the interlayer coupling of perpendicularly magnetized Ni/Cu/Ni(001) trilayers is studied. A crossover in the alignment of the sublayer magnetizations from parallel to antiparallel is observed with increasing temperature, although the interlayer exchange is measured to be antiferromagnetic for all temperatures. The crossover is the result of the competition between the antiferromagnetic interaction and the magnetic anisotropy energy. This Ni/Cu/Ni trilayer with moderate exchange coupling serves as a model for magnetic multilayers in which the interlayer coupling can be switched with temperature. TC 5 BP R14036 EP R14039 PG 4 JI Phys. Rev. B PY 1998 PD JUN 1 VL 57 IS 22 GA ZU948 J9 PHYS REV B UT ISI:000074252500020 ER ##Letoltve [2001.03.14] PT Journal AU Zhou, L Hu, LB Lin, ZF Kawazoe, Y Tao, RB TI Quantum approach for magnetic multilayers at finite temperatures SO PHYSICAL REVIEW B AB The Green's function technique has been employed to examine the finite-temperature properties of a magnetic multilayer both in aligned and in canted spin configurations. A local coordinates system is introduced to describe complicated spin configurations which are determined by minimizing the free energy of the magnetic multilayer. Thermal averages of S-m(Zm) in each layer are selected to be independent variables: and the necessarily self-consistent equations are obtained successfully based on the random phase approximation. The temperature dependences of the coercivity, the hysteresis, and the magnetic multivalued recording have been discussed, and an application of the present approach to the canted spin state is given in a double-film system. TC 4 BP 7863 EP 7869 PG 7 JI Phys. Rev. B PY 1998 PD APR 1 VL 57 IS 13 GA ZH082 J9 PHYS REV B UT ISI:000073070300071 ER #Letoltve: 2001.03.14 PT Journal AU Raquet, B Mamy, R Ousset, JC Negre, N Goiran, M Guerret-Piecourt, C TI Preparation and magnetic properties of the CoO/Co bilayer SO JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS AB The results of the preparation, characterization and magnetic properties of a CoO/Co interface are discussed. This interface was realized by ultraviolet irradiation of a 4 nm Co layer deposited with a gold buffer layer on a GaAs(111) substrate. The Co oxide analyzed by XPS and AFM revealed a continuous 1.7 nm thick layer with a rms roughness of 0.6 nm and mostly CoO at the interface. Longitudinal magneto-optical Kerr loops evidence a strong initial in-plane anisotropy which disappears on oxidation. Values of the unidirectional exchange coupling at the Co/CoO interface were obtained: 0.1 erg/cm(2) from SQUID measurement at 5 K after field cooling and 0.6 erg/cm(2) with magneto-optical Kerr effect in polar configuration from modelization of the M(H) curve. This discrepancy is discussed in terms of the difference of sensing the interfacial coupling in the two cases due to atomic steps. (C) 1998 Elsevier Science B.V. All rights reserved. TC 3 BP 41 EP 48 PG 8 JI J. Magn. Magn. Mater. PY 1998 PD APR VL 184 IS 1 GA ZH109 J9 J MAGN MAGN MATER UT ISI:000073073100004 ER #2001.03.14 letoltve PT Journal AU Lauhoff, G Bruynseraede, C de Boeck, J van Roy, W Bland, JAC Borghs, G TI Ferrimagnetic tau-MnAl/Co superlattices on GaAs SO PHYSICAL REVIEW LETTERS AB We report on the ferrimagnetic superlattice ordering in epitaxial tau-MnAl/Co superlattices on GaAs. For ultrathin Co layers (3.5-7 Angstrom), both the ferromagnetic tau MnAl and Co layers display a large perpendicular magnetic anisotropy together with an antiferromagnetic interface exchange coupling. As a result, an abrupt transition from the ferromagnetically aligned state at saturation to a ferrimagnetic superlattice ordering occurs at unusually high fields (3-7 T) followed by a reversal of the total sample moment at low fields (0.3-1.6 T). TC 1 BP 5290 EP 5293 PG 4 JI Phys. Rev. Lett. PY 1997 PD DEC 29 VL 79 IS 26 GA YN729 J9 PHYS REV LETT UT ISI:000071200000026 ER #Letoltve: 2001.03.14 PT Journal AU Pettit, K Gider, S Parkin, SSP Salamon, MB TI Strong biquadratic coupling and antiferromagnetic-ferromagnetic crossover in NiFe/Cu multilayers SO PHYSICAL REVIEW B AB We report clear manifestations of biquadratic exchange in the magnetoresistance (MR) of (110) single-crystal NiFe/Cu multilayers. Magnetoresistance curves show a low-field MR minimum which results from an asymmetric canting of the moments away from the applied magnetic field. The stability of these magnetic configurations indicates that the biquadratic coupling can be significantly stronger than the bilinear coupling. In samples with ferromagnetic (F) bilinear coupling the strength of both the bilinear and biquadratic coupling decays in the temperature range from 200 to 400 K. In samples that are coupled antiferromagnetically (AF) at room temperature, we observe a crossover from AF to F bilinear coupling as the temperature is lowered below 200 K. We attribute the strong biquadratic coupling and temperature dependence of the bilinear coupling to pinholes in the Cu spacer layers. TC 7 BP 7819 EP 7822 PG 4 JI Phys. Rev. B PY 1997 PD OCT 1 VL 56 IS 13 GA YD866 J9 PHYS REV B UT ISI:A1997YD86600019 ER #Letoltve: 2001.03.14, kinyomtatva PT Journal AU Ma, P Norton, PR TI Growth of ultrathin Fe films on Ge(100): Structure and magnetic properties SO PHYSICAL REVIEW B AB The structure and magnetic properties of ultrathin Fe films grown on Ge(100) at room temperature have been studied by low- energy electron diffraction, Auger electron spectroscopy (AES), angle-resolved AES, and in situ magneto-optical Ken effect (MOKE) measurements. Fe initially grows on Ge(100) in a disordered fashion, with local order commencing around 4 ML. The film grows with a bcc structure for thicknesses greater than 7 ML. Our data are consistent with 6% Ge intermixed in the films. Significant intermixing starts at about 160 degrees C, with rapid diffusion of Fe into the bulk occurring at temperatures higher than 400 degrees C. A single-loop to stepped-loop to single-loop sequence of ferromagnetic loops was observed by MOKE measurements. Hysteresis loop simulations were performed based on the coherent model, the results suggesting that strong in-plane uniaxial anisotropy exists in these films, especially for very thin films. The sequence of loops is due to the increase of the ratio between the cubic anisotropy and the uniaxial anisotropy as the film thickness increases. TC 3 BP 9881 EP 9886 PG 6 JI Phys. Rev. B PY 1997 PD OCT 15 VL 56 IS 15 GA YC391 J9 PHYS REV B UT ISI:A1997YC39100099 ER #Esetleg kell: de kerdes, hogy megvan-e? PT Journal AU Nikitenko, VI Dedukh, LM Gornakov, VS Kabanov, YP Bennett, LH Donahue, MJ Swartzendruber, LJ Shapiro, AJ Brown, HJ TI Spin reorientation transitions and domain structure in magnetic multilayers SO IEEE TRANSACTIONS ON MAGNETICS AB Spin reorientation phase transitions and the evolution of the magnetic phases states arising during magnetization reversal of antiferromagnetic CoNiCu/Cu superlattice are studied using magneto-optical indicator film technique, accompanied by vector hysteresis loop measurements. The spin-flop and nonsymmetric angle phases have been found and analyzed. It is shown that they arise due to the nucleation and growth of domains. TC 3 BP 3661 EP 3663 PG 3 JI IEEE Trans. Magn. PY 1997 PD SEP VL 33 IS 5 PN 2 GA XW565 J9 IEEE TRANS MAGN UT ISI:A1997XW56500053 ER #Mar megvan. Most kinyomtatva. PT Journal AU Yanagihara, H Pettit, K Salamon, MB Kita, E Parkin, SSP TI Magnetoresistance and magnetic properties of Co/Ir multilayers on MgO(110) substrates SO JOURNAL OF APPLIED PHYSICS AB A Co(12 Angstrom)/Ir(16 Angstrom) multilayer deposited on MgO(110) is found to have a strong uniaxial anisotropy, comparable to bulk hcp-Co. Experimental results suggests the crystallographic relation of (100)[001]Co/(110)[001]Ir/(110)[001]MgO. A remarkable difference is seen between easy and hard axis magnetization processes, due to competition between the in-plane anisotropy and the exchange coupling. Considering the characteristics of the MH loops and magnetoresistance curves, we simulate the magnetization and magnetoresistance processes numerically. The results of our simulation indicate the existence of biquadratic coupling in Co/Ir(110). (C) 1997 American Institute of Physics. TC 4 BP 5197 EP 5199 PG 3 JI J. Appl. Phys. PY 1997 PD APR 15 VL 81 IS 8 PN 2B GA WV537 J9 J APPL PHYS UT ISI:A1997WV53700178 ER #2001.03.14: Uniaxialis anizotropia, de olyan anyagokkal, ami nekunk nincsen. #Erdekes lehet a kesobbiekben, ha a modellunket akarjuk fittelni -> megvannak #a rendszer parameterei. Letoltve, kinyomtatva. PT Journal AU Zhao, HW Chen, Y Zhu, WR Dong, GS Jin, XF Lu, M Zhai, HR TI Epitaxial structure and magnetic anisotropies of metastable single crystal Co0.70Mn0.30 film SO JOURNAL OF APPLIED PHYSICS AB Alloy films of Co0.70Mn0.30 were grown on GaAs (001) substrates by molecular beam epitaxy at room temperature. The metastable tetragonally distorted single crystal structure was confirmed by reflection high energy electron diffraction and x-ray diffraction measurement, which exhibited a 2.87 Angstrom in- plane lattice parameter. Ferromagnetic resonance measurements and theoretical fitting were performed and showed that, with a Mn capping layer, a uni-directional anisotropy existed. In addition, a fourfold tetragonal magnetocrystalline anisotropy as well as a uniaxial term in the film plane was also confirmed. The hysteresis loops recorded by longitudinal magneto-optical Kerr-effect also demonstrated the existence of different kinds of in-plane magnetic anisotropy. The origins of the anisotropy are explained tentatively. (C) 1997 American Institute of Physics. TC 1 BP 2036 EP 2038 PG 3 JI J. Appl. Phys. PY 1997 PD FEB 15 VL 81 IS 4 GA WH339 J9 J APPL PHYS UT ISI:A1997WH33900066 ER #Erdekes lehet, de nincs JETP letters! -> oroszoknal kell majd megnezni! PT Journal AU Dedukh, LM Gornakov, VS Kabanov, YP Nikitenko, VI TI Direct experimental investigation of spin-reorientation phase transitions in an antiferromagnetic CoNiCu/Cu superlattice SO JETP LETTERS AB The characteristic features of phase transitions induced by an external magnetic field and of the corresponding changes in the relative orientations of the spins in the ferromagnetic CoNiCu layers of a multilayer film, which are coupled by an antiferromagnetic exchange interaction via nonmagnetic Cu interlayers, are studied using a magnetooptic method for visualizing the fringing fields. It is established that the magnetization reversal process in this nanocomposite material proceeds by a spin-flop orientational phase transition on account of the formation and motion of specific domain walls as well as by incoherent rotation of the spins toward the applied field. It is shown that, depending on the direction of the external magnetic field with respect to the easy axis, asymmetric canted phases also arise as a result of such transitions. (C) 1996 American Institute of Physics. TC 2 BP 826 EP 831 PG 6 JI Jetp Lett. PY 1996 PD DEC 10 VL 64 IS 11 GA WD834 J9 JETP LETT-ENGL TR UT ISI:A1996WD83400008 ER #2001.03.14 Már biztosan megvan. Fe/Cr-nál volt. PT Journal AU Ustinov, VV Bebenin, NG Romashev, LN Minin, VI Milyaev, MA Del, AR Semerikov, AV TI Magnetoresistance and magnetization of Fe/Cr(001) superlattices with noncollinear magnetic ordering SO PHYSICAL REVIEW B AB We study the magnetization and magnetoresistance of superlattices with biquadratic exchange. The equilibrium states are analyzed on the base of the free energy expression that includes all terms up to the fourth order in components of magnetizations of magnetic sublattices. The con-elation between the magnetization curve and the magnetoresistance for various orientation of magnetic field relative to the film plane is established. The experimental studies are made on the samples of molecular-beam epitaxy grown Fe/Cr superlattices. The positive magnetoresistance was found for the perpendicular-to- plane magnetic field. It is shown that this effect as well as the characteristic features of the magnetization curves are connected with the noncollinear magnetic alignment, which exists in our samples, and the fourth order magnetic anisotropy of unfamiliar type. TC 18 BP 15958 EP 15966 PG 9 JI Phys. Rev. B PY 1996 PD DEC 1 VL 54 IS 22 GA VX718 J9 PHYS REV B UT ISI:A1996VX71800057 ER #2001.03.14: KFKI konyvtarból kimásolni. PT Journal AU Postava, K Bobo, JF Ortega, MD Raquet, B Jaffres, H Snoeck, E Gorian, M Fert, AR Redoules, JP Pistora, J Ousset, JC TI Magneto-optical measurements of magnetization reversal in nanometer scale sputtered Fe thin films SO JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS AB We present a magneto-optical study of the magnetic behavior of sputtered iron films of various thickness ranging from 2 to 50 nm grown on a silicon substrate. First we calculate the reflection coefficients in the case of an homogeneous magneto- optical layer with in-plane magnetization. Then we describe a technique in which both in-plane magnetization components are detected. Because of the axial deposition procedure, iron films exhibit in-plane uniaxial anisotropy depending on the thickness of the layer. In particular, we show that, for 4 nm thickness, anistropy induced by slightly tilted columnar growth can be observed, whereas for larger thicknesses this in-plane anisotropy vanishes. Using an accurate acquisition system based upon a rapid analog-to-digital converter we measured the rapid magnetization reversal. The field sweep rate was varied between 100 Oe/s and 1 MOe/s. We interpret the observed dynamical effects in terms of wall movement and microdomain reversal. TC 9 BP 8 EP 20 PG 13 JI J. Magn. Magn. Mater. PY 1996 PD OCT VL 163 IS 1-2 GA VW289 J9 J MAGN MAGN MATER UT ISI:A1996VW28900003 ER #2001.03.14: Erdekes -> esetleg igy is lehet uniaxialis anizotropiat csinalni? #Kerdes, hogy annak milyen lenne az alakja... #Konyvtarbol elkerni. PT Journal AU Young, S Dieny, B Rodmacq, B Mouchot, J Vaudaine, MH TI Magnetoresistance of microscopic strips of thin (NiFe/Ag) multilayers with large bi-quadratic coupling SO JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS AB The magnetoresistance of microscopic strips of (NiFe/Ag) multilayers with large bi-quadratic coupling has been measured. When the field is applied along the length of the strip, the magnetoresistance has an almost linear R(H) characteristic. On the other hand, when the field is applied transversely i.e. in the plane of the film but perpendicular to its length, a plateau in the resistivity is observed up to a critical field, H-crit, which depends on the shape anisotropy of the strip. Above this field, R(H) decreases as in the longitudinal case, Computer simulations have been undertaken to explain this behaviour. The plateau observed with a transverse applied field is due to the effect of the shape anisotropy on the remanent magnetization of the multilayers. This remanent magnetization can be quite large because of the significant bi-quadratic coupling between the layers. TC 3 BP 38 EP 42 PG 5 JI J. Magn. Magn. Mater. PY 1996 PD SEP VL 162 IS 1 GA VR940 J9 J MAGN MAGN MATER UT ISI:A1996VR94000005 ER #2001.03.14: #Erdekes lehet, bar csak 1 hivatkozas erkezett rá. #Ha osszefoglalo fázisdiagrammot készítünk a csatolásokról. #KFKI könyvtárból kimásolni. PT Journal AU Bebenin, NG TI Ferromagnetic resonance in a magnetic trilayer with biquadratic exchange and unidirectional anisotropy SO JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS AB Stable states in a trilayer with a bilinear and biquadratic exchange interaction between ferromagnetically ordered layers and with strong unidirectional anisotropy are studied theoretically. It is shown that, in spin valves of this type, there may be a number of phase transitions of first or second order, and in the former case the width of the hysteresis loop is determined by biquadratic exchange. In the vicinity of the critical field the magnetic dynamics of the layer is shown to be approximately independent of that of other layers. TC 1 BP 65 EP 69 PG 5 JI J. Magn. Magn. Mater. PY 1996 PD AUG VL 161 GA VR562 J9 J MAGN MAGN MATER UT ISI:A1996VR56200011 ER #2001.03.14: Elmeleti, erdekes: A ra valo hivatkozasokat (18 darab) kigyujteni!!! Leuvenben, vagy itthon. #A fenti mondatot a konyvtarazashoz beirni (kigyujtes!) + #FOLYTATNI!!! PT Journal AU Moschel, A Hyman, RA Zangwill, A Stiles, MD TI Magnetization reversal in ultrathin films with monolayer-scale surface roughness SO PHYSICAL REVIEW LETTERS AB The intrinsic anisotropy of nominally flat, ultrathin ferromagnetic films typically is augmented by a uniaxial anisotropy at step edges. We report model calculations of hysteresis for such systems with inplane magnetization and monolayer-scale roughness. The reversal process: is,a combination of domain nucleation at step edges, expansion of these domains through morphological constrictions, and coherent rotation within domains. The initiation of reversal at well separated step edges can explain the very small coercive fields measured for real ultrathin magnetic films. TC 18 BP 3653 EP 3656 PG 4 JI Phys. Rev. Lett. PY 1996 PD OCT 21 VL 77 IS 17 GA VM890 J9 PHYS REV LETT UT ISI:A1996VM89000042 ER PT Journal AU Khapikov, AF TI Interlayer exchange coupling and non-uniform magnetization processes in magnetic multilayers SO JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS AB The magnetization curves associated with domain wall translation in magnetic bilayers with antiferromagnetic coupling are calculated. New features contrasting with the magnetization processes for single layers are found. First, the virgin magnetization curves are characterized by an intrinsic coercivity that has its origin in the interlayer exchange coupling. Second, the magnetization curves of bilayers demonstrate a hysteresis due to the exchange interaction potential between domain walls in adjacent layers, We show also how tile exchange coupling constant can be evaluated from the magnetization curve measurements. TC 0 BP 130 EP 132 PG 3 JI J. Magn. Magn. Mater. PY 1996 PD APR VL 156 IS 1-3 GA UV358 J9 J MAGN MAGN MATER UT ISI:A1996UV35800054 ER PT Journal AU Gester, M Daboo, C Hicken, RJ Gray, SJ Ercole, A Bland, JAC TI Continuous evolution of the in-plane magnetic anisotropies with thickness in epitaxial Fe films SO JOURNAL OF APPLIED PHYSICS AB We have studied the evolution of the magnetic in-plane anisotropy in epitaxial Fe/GaAs films of both (001) and ((1) over bar 10) orientation as a function of the Fe layer thickness using the longitudinal magneto-optic Kerr effect and Brillouin light scattering. Magnetization curves which are recorded in situ during film growth reveal a continuous change of the net anisotropy axes with increasing film thickness. This behavior can be understood to arise from the combination of a uniaxial and a cubic in-plane magnetic anisotropy which are both thickness dependent. Structural analysis of the substrate and Fe film surfaces provides insight into the contribution of atomic steps at the interfaces to the magnetic anisotropy. Changing the degree of crystalline order at the Fe-GaAs interface allows us to conclude that the magnetic anisotropies are determined by atomic scale order. (C) 1996 American Institute of Physics. TC 34 BP 347 EP 355 PG 9 JI J. Appl. Phys. PY 1996 PD JUL 1 VL 80 IS 1 GA UU532 J9 J APPL PHYS UT ISI:A1996UU53200053 ER PT Journal AU HICKEN, RJ DABOO, C GESTER, M IVES, AJR GRAY, SJ BLAND, JAC TI INTERLAYER EXCHANGE COUPLING IN EPITAXIAL FE/CR/FE/AG/GAAS(100) STRUCTURES SO JOURNAL OF APPLIED PHYSICS AB The interlayer exchange coupling has been investigated in epitaxial Fe(20 Angstrom)/Cr/Fe(20 Angstrom)/Ag/GaAs(100) structures that contain a wedge-shaped (0-40 Angstrom) Cr layer. Longitudinal and polar magneto-optical Kerr-effect (MOKE) and Brillouin light-scattering measurements have been combined to determine values for the relevant anisotropy constants and both the bilinear and biquadratic coupling strengths. The phase and period of the oscillations in the interlayer coupling are found to agree well with those reported by other researchers while the total coupling strength is found to be reduced. This reduction is presumably due to the presence of structural imperfections in our samples, and our results may therefore be of use in testing some of the recently proposed extrinsic biquadratic coupling mechanisms. Specifically, we find that for the Cr thicknesses studied the biquadratic coupling strength in our samples varies as d(Cr)(-1.4) where d(Cr) is the thickness of the Cr layer, We also present results that show how the ultrathin Cr limit may be investigated. We show that the coercivity of the easy axis MOKE loops is sensitive to submonolayer coverages of Cr and that polar MOKE is sensitive to the strong ferromagnetic coupling found in the 0-4 Angstrom Cr thickness range. (C) 1995 American Institute of Physics. TC 15 BP 6670 EP 6678 PG 9 JI J. Appl. Phys. PY 1995 PD DEC 1 VL 78 IS 11 GA TH851 J9 J APPL PHYS UT ISI:A1995TH85100044 ER PT Journal AU TANUMA, T TAKAHASHI, S MAEDA, A KUME, M KUROKI, K TI STEEP MR CHANGE IN NIFE/CU/CO TRILAYERS SO IEEE TRANSACTIONS ON MAGNETICS AB A field sensitivity of about 2%/Oe in magnetoresistance (MR) change has been observed in NiFe(6 nm)/Cu/Co(5 nm) trilayers. The MR change was accompanied with a sharp increase in resistivity before decreasing steeply for increasing fields. Thickness of the Cu spacer layer influenced the sensitivity of MR change. These results suggest an existence of interlayer coupling between the two magnetic layers. An analysis of this MR effect suggests that biquadratic coupling plays an important role in the steep MR change. TC 1 BP 3955 EP 3957 PG 3 JI IEEE Trans. Magn. PY 1995 PD NOV VL 31 IS 6 PN 2 GA TD558 J9 IEEE TRANS MAGN UT ISI:A1995TD55800168 ER PT Journal AU BENNETT, LH MCMICHAEL, RD SWARTZENDRUBER, LJ HUA, S LASHMORE, DS SHAPIRO, AJ GORNAKOV, VS DEDUKH, LM NIKITENKO, VI TI DYNAMICS OF DOMAIN-STRUCTURE IN MAGNETIC MULTILAYERS SO IEEE TRANSACTIONS ON MAGNETICS AB We use a new method for visualization and direct experimental study of dynamic magnetization processes and for nondestructive characterization of the defect structure of magnetic multilayers. The method utilizes a transparent indicator ferrimagnetic magneto-optic film with in-plane anisotropy. An example of its application to the investigation of the magnetization reversal by domain wall motion in electrochemically produced CoNiCu/Cu multilayers which exhibit a giant magnetoresistance effect is described. TC 4 BP 4088 EP 4090 PG 3 JI IEEE Trans. Magn. PY 1995 PD NOV VL 31 IS 6 PN 2 GA TD558 J9 IEEE TRANS MAGN UT ISI:A1995TD55800210 ER PT Journal AU FENG, JW KANG, SS PAN, FM JIN, GJ LU, M HU, A JIANG, SS FENG, D TI MAGNETIC-ANISOTROPY AND INTERLAYER EXCHANGE COUPLING IN THE SPUTTERED CO/AG MULTILAYERS SO JOURNAL OF APPLIED PHYSICS AB The in-plane uniaxial anisotropy and perpendicular anisotropy of sputtered Co/Ag(111) multilayers have been investigated by magnetic measurements and the in-plane ferromagnetic resonance (FMR) technique. The data-fitting analysis for the FMR experimental results about the angular dependence of the resonance field shows that the in-plane anisotropy cannot be fully described by only using the first-order term, and the second-order term must be included. Furthermore, the interface- induced anisotropy has been obtained by FMR. Both ferromagnetic and antiferromagnetic couplings have been revealed by hysteresis loop measurement. Specifically, a spin-flip phase transition has been observed in. the sputtered Co/Ag(111) multilayers, which is attributed to the effects of the AF- coupling and in-plane uniaxial anisotropy. (C) 1995 American Institute of Physics. TC 2 BP 5549 EP 5553 PG 5 JI J. Appl. Phys. PY 1995 PD NOV 1 VL 78 IS 9 GA TB545 J9 J APPL PHYS UT ISI:A1995TB54500050 ER PT Journal AU DINIA, A BAILLY, J OUNADJELA, K STOEFFLER, D TI MAGNETIZATION CURVES SIMULATION IN CO/RU SUPERLATTICES SO SOLID STATE COMMUNICATIONS AB Magnetization curves simulations are reported for [Co10 AngstromRux](n), superlattices with different Ru thicknesses x = 10, 20, 28 and 32 Angstrom. These samples present both a perpendicular anisotropy and an antiferromagnetic exchange coupling. The numerical calculations were performed using a model expressing the energy as a function of the relative orientation of the magnetization not only between Co layers separated by Ru but also within the Co layers themselves. Each Co magnetic layer is divided into three magnetic parts : (i) Two of them whose moments are antiferromagnetically coupled through the Ru layer correspond to the ''interfacial'' planes. (ii) The third one represents the inner planes whose moments are ferromagnetically coupled to the interfacial ones. The results are in good agreement with the experimental curves and show that the model allows a good description of the particular magnetization curves which saturate in two stages : a rapid saturation of about 80 % of the total magnetization, followed by a slow increase up to very high fields until the total saturation is reached. TC 0 BP 549 EP 555 PG 7 JI Solid State Commun. PY 1995 PD NOV VL 96 IS 8 GA RY700 J9 SOLID STATE COMMUN UT ISI:A1995RY70000004 ER PT Journal AU RAQUET, B ORTEGA, MD GOIRAN, M FERT, AR REDOULES, JP MAMY, R OUSSET, JC SDAQ, A KHMOU, A TI DYNAMICAL PROPERTIES OF MAGNETIZATION REVERSAL IN AN ULTRATHIN AU/CO FILM SO JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS AB We present a dynamical study of hysteresis loops of a MoS2/[Au/Co/Au] sandwich performed by surface magneto-optical Kerr effect with a field variation rate up to 1.2 MOe/s. An interpretation of dynamical effects at room temperature is proposed, using a modelization of the magnetization reversal. We discuss simulations which describe two different processes of the magnetization reversal to interpret the evolution of the hysteresis loops for several rates of variation of the magnetic field. For a first range of field variation rates lower than 180 kOe/s, the predominant mechanism seems to be wall motion and beyond 180 kOe/s, an expression for the magnetization is given, which supposes micro-domains reversal as a prevailing process. Finally, the general behaviour of the relaxation time, depending on the magnetic field, is investigated. TC 11 BP L5 EP L12 PG 8 JI J. Magn. Magn. Mater. PY 1995 PD SEP VL 150 IS 1 GA RY184 J9 J MAGN MAGN MATER UT ISI:A1995RY18400003 ER PT Journal AU YANG, ZJ SCHEINFEIN, MR TI INTERFACIAL-ROUGHNESS EFFECTS ON GIANT MAGNETORESISTANCE AND INTERLAYER COUPLING IN CO/CU SUPERLATTICES SO PHYSICAL REVIEW B AB Giant magnetoresistance and interlayer exchange coupling in Co/Cu superlattices grown by e-beam evaporation have been investigated by using the combined three-axis magneto-optical Kerr effect, magnetotransport measurements, x-ray diffraction, Rutherford backscattering, transmission electron microscopy (TEM), and domain observation with scanning transmission electron microscope electron holography. Large-angle x-ray scattering data and TEM images indicate that the superlattices have fee (111) orientation with polycrystalline grain sizes ranging from 10-14 nm. Small angle x-ray scattering and cross- section TEM images show that the superlattices have a well- defined layer structure, coherent grain-to-grain epitaxial growth, and interfacial roughness of +/-0.2-0.4 mm. The correlations between the 90 degrees magnetization and magnetoresistance oscillation curves suggest that the giant magnetoresistance in superlattices with imperfect interfaces results from the 90 degrees orientation of domains within adjacent Co layers. TC 17 BP 4263 EP 4274 PG 12 JI Phys. Rev. B PY 1995 PD AUG 1 VL 52 IS 6 GA RQ075 J9 PHYS REV B UT ISI:A1995RQ07500064 ER PT Journal AU BLAND, JAC DABOO, C GEHRING, GA KAPLAN, B IVES, AJR HICKEN, RJ JOHNSON, AD TI MAGNETIZATION OF ULTRATHIN FERROMAGNETIC-FILMS AT FINITE TEMPERATURES SO JOURNAL OF PHYSICS-CONDENSED MATTER AB The in-plane magnetization of a two-dimensional film may be stabilized by either dipolar interactions or by an in-plane anisotropy in the absence of an external field. We have calculated the conditions for either of these effects to dominate and show that there is only a restricted range of q values in which dipolar effects are important before the exchange dominates. We report measurements of all relevant anisotropy fields for an epitaxial Ag/2 ML Co/Ag(001) film structurally characterized by angle-resolved Auger spectroscopy and low-energy electron diffraction, together with a measurement of the ground state moment per Co atom (enhanced from the bulk value) using polarized neutron reflection. The results allow us to extend our previous study of the temperature dependence of the magnetization by including the perpendicular fields and the field dependence of the magnetization at 300 K. We show that the field dependence of the magnetization is not consistent with a spin wave gap due to dipolar interactions but is consistent with an anisotropy- induced spin wave gap, confirming the results of a preliminary study. TC 6 BP 6467 EP 6476 PG 10 JI J. Phys.-Condes. Matter PY 1995 PD AUG 7 VL 7 IS 32 GA RN934 J9 J PHYS-CONDENS MATTER UT ISI:A1995RN93400012 ER PT Journal AU PARKIN, SSP TI GIANT MAGNETORESISTANCE IN MAGNETIC NANOSTRUCTURES SO ANNUAL REVIEW OF MATERIALS SCIENCE AB This chapter contains a brief review of the giant magnetoresistance (GMR) effect exhibited by magnetic multilayers, granular alloys, and related materials. Subjects covered include a description of the phenomenon, and the related oscillatory interlayer exchange coupling in magnetic multilayers; a simple model of giant magnetoresistance; the inverse GMR effect in spin-engineered magnetic multilayers; structures that display large changes in resistance in small magnetic fields, possibly for use in magnetic field sensors; and the dependence of GMR on various aspects of the magnetic structures. TC 25 BP 357 EP 388 PG 32 JI Annu. Rev. Mater. Sci. PY 1995 VL 25 GA RM745 J9 ANNU REV MATER SCI UT ISI:A1995RM74500016 ER PT Journal AU COCHRAN, JF TI MAGNETIZATION REVERSAL IN A THIN FERROMAGNETIC FILM WEAKLY EXCHANGE-COUPLED TO A BULK FERROMAGNET SO JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS AB The static magnetization distribution in a thin film and in a bulk magnet has been calculated using a simplified model in which the ferromagnetic thin film is coupled to the bulk magnet through a contact exchange interaction. The lowest lying frequencies of oscillation of the magnetization around this equilibrium configuration have also been calculated. It has been shown that for weak antiferromagnetic coupling, and assuming that the system adopts a configuration corresponding to a state of lowest free energy, there exists a range of applied magnetic field strengths for which the magnetization orientation in the thin film deviates from the applied field direction. In the state characterized by this non-parallel thin film magnetization, the magnetization orientations both in the thin film and in the bulk magnet become position dependent. For a 20 monolayer iron Nm the twist in magnetization orientation is similar to 1-3 degrees for exchange coupling strengths ranging from 0.5-1.5 erg/cm(2). The magnetization in the bulk is twisted a few degrees from the applied field direction at the bulk surface, and the angle through which the magnetization is turned decays towards zero for distances progressively deeper into the bulk magnet. The decay length is similar to 100 Angstrom for iron. Calculated magnetic field dependencies for the thin film frequency are found to be in reasonable agreement with data reported for 20 ML Fe(001) films exchange coupled through Cr(001) to a Fe(001) whisker. TC 11 BP 101 EP 114 PG 14 JI J. Magn. Magn. Mater. PY 1995 PD MAY VL 147 IS 1-2 GA RD488 J9 J MAGN MAGN MATER UT ISI:A1995RD48800015 ER PT Journal AU DABOO, C HICKEN, RJ GU, E GESTER, M GRAY, SJ ELEY, DEP AHMAD, E BLAND, JAC PLOESSL, R CHAPMAN, JN TI ANISOTROPY AND ORIENTATIONAL DEPENDENCE OF MAGNETIZATION REVERSAL PROCESSES IN EPITAXIAL FERROMAGNETIC THIN-FILMS SO PHYSICAL REVIEW B TC 26 BP 15964 EP 15973 PG 10 JI Phys. Rev. B PY 1995 PD JUN 15 VL 51 IS 22 GA RD552 J9 PHYS REV B UT ISI:A1995RD55200031 ER PT Journal AU PARK, YS FULLERTON, EE BADER, SD TI GROWTH-INDUCED UNIAXIAL INPLANE MAGNETIC-ANISOTROPY FOR ULTRATHIN FE DEPOSITED ON MGO(001) BY OBLIQUE-INCIDENCE MOLECULAR-BEAM EPITAXY SO APPLIED PHYSICS LETTERS TC 11 BP 2140 EP 2142 PG 3 JI Appl. Phys. Lett. PY 1995 PD APR 17 VL 66 IS 16 GA QT728 J9 APPL PHYS LETT UT ISI:A1995QT72800044 ER PT Journal AU SAKAKIMA, H SATOMI, M ONAKA, K YAMAMOTO, S TI ANISOTROPIC LOW-FIELD GIANT MAGNETORESISTANCE IN [NI-FE-CO/CU] MULTILAYERS SO JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS AB [Ni-Fe-Co(3 nm)/Cu(2 nm)] multilayers having in-plane uniaxial magnetic anisotropy were prepared by using a carousel type sputtering apparatus. The MR (magnetoresistance) ratio was about 8% and the MR curve along the easy axis showed a sharp split hysteresis with a very small transient field, Delta H similar to 3 Oe, though the switching is irreversible. The experimental results are discussed by using magnetic phase diagrams calculated by Dieny et al. (1990) and Folkerts (1991). TC 9 BP L268 EP L272 PG 5 JI J. Magn. Magn. Mater. PY 1995 PD MAR VL 145 IS 3 GA QR549 J9 J MAGN MAGN MATER UT ISI:A1995QR54900002 ER PT Journal AU BLOEMEN, PJH VANDEVORST, MTH DEJONGE, WJM JOHNSON, MT COEHOORN, R TI MAGNETIC LAYER THICKNESS DEPENDENCE OF THE INTERLAYER EXCHANGE COUPLING SO MODERN PHYSICS LETTERS B AB Recent progress in the research on interlayer exchange coupling, focusing on the effect of the magnetic layer, is reviewed. Several theoretical works have shown that the exchange coupling does not just involve an interaction localized at the interfaces, but the electronic properties of the sandwich as a whole. The important prediction that the strength of the exchange coupling should oscillate as a function of the magnetic layer thickness has been confirmed recently for the Co/Cu(100) and the Fe/Cr(100) system. The oscillation periods are strongly believed to be related to wave vectors that span extremal parts of the spin-resolved Fermi surfaces of the ferromagnets. TC 4 BP 1 EP 25 PG 25 JI Mod. Phys. Lett. B PY 1995 PD JAN 10 VL 9 IS 1 GA QL606 J9 MOD PHYS LETT B UT ISI:A1995QL60600001 ER PT Journal AU FUJIWARA, H DOYLE, WD MATSUZONO, A PARKER, MR TI THE EFFECT OF BIQUADRATIC EXCHANGE COUPLING ON THE MAGNETIZATION CONFIGURATION IN MULTILAYERED FILMS SO JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS AB The effect of biquadratic exchange coupling (J(2)) on the magnetization configuration in multilayered GMR films as a function of field in the easy and hard directions has been investigated. The complexity of the configurations caused by J(2) may explain varieties of hysteresis and GMR curves obtained experimentally. Transverse biased permeability measurements make it possible to estimate both the bilinear (J(1)) and biquadratic (J(2)) effective fields. TC 1 BP 519 EP 520 PG 2 JI J. Magn. Magn. Mater. PY 1995 PD FEB VL 140 PN 1 GA QL736 J9 J MAGN MAGN MATER UT ISI:A1995QL73600249 ER PT Journal AU KANO, H OKABE, A KAGAWA, K SUZUKI, A YAOI, T HAYASHI, K TI GROWTH INDUCED INPLANE ANISOTROPY IN SPUTTERED FECONI/CU GIANT MAGNETORESISTANCE MULTILAYERS SO JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS AB The origin of growth induced in-plane magnetic anisotropy in sputtered FeCoNi/Cu multilayers was investigated. The anisotropy exceeded 10 Oe when the multilayers were prepared on a substrate which successively rotated over each gun. This was caused by a linear distribution of the crystalline orientation. TC 1 BP 553 EP 554 PG 2 JI J. Magn. Magn. Mater. PY 1995 PD FEB VL 140 PN 1 GA QL736 J9 J MAGN MAGN MATER UT ISI:A1995QL73600265 ER PT Journal AU UTOCHKIN, SN ZVEZDIN, AK TI SPIN-REORIENTATION TRANSITIONS IN RE-TM SUPERLATTICES SO JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS AB Spin-reorientation phase transitions in rare earth-transition metal (RE-TM) magnetic superlattices are studied theoretically. The magnetic phase diagram is constructed for the case of a magnetization process along the easy axis. The feature of the model considered is to take into account finite-size effects. The phase transitions in RE-TM superlattices with isotropic and anisotropic surface layers are discussed. TC 1 BP 787 EP 788 PG 2 JI J. Magn. Magn. Mater. PY 1995 PD FEB VL 140 PN 2 GA QM074 J9 J MAGN MAGN MATER UT ISI:A1995QM07400025 ER PT Journal AU GANGOPADHYAY, S HOSSAIN, S YANG, J BARNARD, JA KIEF, MT FUJIWARA, H PARKER, MR TI HIGH-SENSITIVITY GMR IN NIFECO/CU MULTILAYERS SO JOURNAL OF APPLIED PHYSICS TC 6 BP 6522 EP 6524 PG 3 JI J. Appl. Phys. PY 1994 PD NOV 15 VL 76 IS 10 PN 2 GA PT848 J9 J APPL PHYS UT ISI:A1994PT84800162 ER PT Journal AU BLOEMEN, PJH VANKESTEREN, HW SWAGTEN, HJM DEJONGE, WJM TI OSCILLATORY INTERLAYER EXCHANGE COUPLING IN CO/RU MULTILAYERS AND BILAYERS SO PHYSICAL REVIEW B TC 12 BP 13505 EP 13514 PG 10 JI Phys. Rev. B PY 1994 PD NOV 1 VL 50 IS 18 GA PT410 J9 PHYS REV B UT ISI:A1994PT41000049 ER PT Journal AU LENCZOWSKI, SKJ GIJS, MAM GIESBERS, JB VANDERVEERDONK, RJM DEJONGE, WJM TI INTERPRETATION OF THE GIANT MAGNETORESISTANCE EFFECT IN CO/CU(100) MULTILAYERS WITH THE QUANTUM MODEL OF GIANT MAGNETORESISTANCE SO PHYSICAL REVIEW B AB We have measured the magnetoresistance of high-vacuum-sputtered Co/Cu(100) multilayers grown on Cu buffer layers. The magnetoresistance in the first antiferromagnetic- (AF-) coupling peak is very sensitive to the buffer layer thickness. We find a linear dependence between the actual measured magnetoresistance and the fraction of AF coupling, as determined by magnetization measurements. We compare our Co/Cu(100) magnetoresistance data at 4 K of completely antiparallel-aligned multilayers with the quantum model of giant magnetoresistance of Levy, Zhang, and Fert. This reveals evidence for strong spin-dependent interface scattering, whereas the spin dependence of the bulk scattering in Co is small. TC 28 BP 9982 EP 9988 PG 7 JI Phys. Rev. B PY 1994 PD OCT 1 VL 50 IS 14 GA PL951 J9 PHYS REV B UT ISI:A1994PL95100036 ER PT Journal AU HICKEN, RJ IVES, AJR ELEY, DEP DABOO, C BLAND, JAC TI INTERLAYER EXCHANGE COUPLING AND WEAKENED SURFACE EXCHANGE IN ULTRATHIN EPITAXIAL FE(100)/PD(100)MGO(100) STRUCTURES SO PHYSICAL REVIEW B AB Brillouin light scattering (BLS) and the polar magneto-optic Kerr effect (MOKE) have been used to determine the interlayer exchange coupling strength at room temperature in an epitaxial wedge sample of nominal structure Pd/Fe(20 angstrom)/Pd/Fe(10 angstrom)/MgO(100) in which the Pd interlayer thickness varied between 14 and 30 angstrom. The constituent Fe layers were chosen to have different thicknesses and hence possessed different perpendicular anisotropy fields. This allowed both acoustic and optical spin-wave modes to be observed in the BLS experiment and also meant that the polar MOKE experiment could in principle be used to determine both antiferromagnetic and ferromagnetic interlayer coupling strengths. In order that the magnetic parameters of the individual Fe layers be independently determined, superconducting-quantum-interference- device (SQUID) magnetometry, in-plane MOKE, polar MOKE, and BLS measurements have also been made upon reference samples of nominal structure Pd/Fe(20 angstrom)/Pd(150 angstrom)/Fe(10 angstrom)/MgO(100) and Pd/Fe(10 angstrom)/MgO(100). Comparison of BLS and polar MOKE for the reference samples revealed different values for the effective demagnetizing fields in the two experiments. This is discussed in terms of a possible weakened surface exchange interaction at the Fe/Pd interface. For the wedge structure, ferromagnetic interlayer exchange coupling was observed for the entire range of Pd thicknesses studied. TC 14 BP 6143 EP 6150 PG 8 JI Phys. Rev. B PY 1994 PD SEP 1 VL 50 IS 9 GA PG285 J9 PHYS REV B UT ISI:A1994PG28500040 ER PT Journal AU DIENY, B VEDYAYEV, A TI CROSSOVER FROM EASY-PLANE TO PERPENDICULAR ANISOTROPY IN MAGNETIC THIN-FILMS - CANTED ANISOTROPY DUE TO PARTIAL COVERAGE OR INTERFACIAL ROUGHNESS SO EUROPHYSICS LETTERS AB Crossovers from easy-plane to perpendicular anisotropy have been observed in numerous magnetic bilayers comprised of thin Co or Fe layers covered with transition or noble metals. We show that spatial fluctuations in the thickness of the magnetic or non-magnetic layers amounting to one atomic monolayer can give rise to a canted anisotropy. Phenomenologically, this anisotropy is expressed via a 45-degrees anisotropy term - K45- degrees sin2 (2theta) which is present in addition to the usual uniaxial anisotropy. TC 5 BP 723 EP 728 PG 6 JI Europhys. Lett. PY 1994 PD MAR 20 VL 25 IS 9 GA NE004 J9 EUROPHYS LETT UT ISI:A1994NE00400015 ER PT Journal AU SCHREIBER, F SOLIMAN, A BODEKER, P MECKENSTOCK, R BROHL, K PELZL, J GARIFULLIN, IA TI ANISOTROPY STUDIES ON MOLECULAR-BEAM-EPITAXY-GROWN CO(111) THIN-FILMS BY FERROMAGNETIC-RESONANCE SO JOURNAL OF APPLIED PHYSICS AB ne magnetic anisotropy of Co/Cu(111) thin films has been investigated using the ferromagnetic resonance (FMR) technique. The films were prepared by molecular-beam epitaxy in ultrahigh vacuum on sapphire substrates with niobium as a buffer layer. In situ RHEED investigations, ex situ x-ray low-angle reflectivity measurements, and high-angle Bragg scans confirm the structural quality of the films. Angular dependent FMR measurements are performed in the plane of the films and out- of-plane. The angular dependence of the line positions in-plane shows a competition between the sixfold anisotropy, which is expected for bulk Co, and a twofold anisotropy contribution. It is demonstrated that by FMR one can detect even small values of the higher-order anisotropy terms. In the analysis, we put emphasis on the relationship between magnetic and structural properties. TC 6 BP 6492 EP 6494 PG 3 JI J. Appl. Phys. PY 1994 PD MAY 15 VL 75 IS 10 PN 2B GA NN736 J9 J APPL PHYS UT ISI:A1994NN73600104 ER PT Journal AU DABOO, C HICKEN, RJ ELEY, DEP GESTER, M GRAY, SJ IVES, AJR BLAND, JAC TI MAGNETIZATION REVERSAL PROCESSES IN EPITAXIAL FE/GAAS(001) FILMS SO JOURNAL OF APPLIED PHYSICS AB In this article we present the results of a detailed study of the switching behavior observed in epitaxial single Fe films of thickness between 30 and 450 angstrom, and a wedge shaped Fe film with a thickness range of 10-60 angstrom grown on GaAs (001). These films have cubic and uniaxial anisotropies which change with film thickness. For the fixed thickness films the values of the anisotropy constants were accurately determined by Brillouin light scattering (BLS) measurements together with polar magneto-optic Kerr effect (MOKE) measurements that gave the value of the magnetization. The switching behavior of these samples was observed with in-plane MOKE magnetometry as a function of the angle between the applied field and the in- plane crystallographic axes. Measurements of the component of magnetization perpendicular to the applied field allow a precise determination of the relative orientation of the hard and easy in-plane anisotropy axes. This can be used to accurately determine the ratio of uniaxial to cubic anisotropy constants, when this ratio is less than one. The ratios obtained from MOKE agree well with those obtained from BLS. Minimum energy calculations predict that the reversal process should proceed by a continuous rotation of the magnetization vector with either one or two irreversible jumps, depending on the applied field orientation and the nature of the anisotropy of the film. The calculations provide a good qualitative description of the observed reversal process, although the magnetic microstructure influences the exact values of the switching fields. TC 21 BP 5586 EP 5588 PG 3 JI J. Appl. Phys. PY 1994 PD MAY 15 VL 75 IS 10 PN 2A GA NN734 J9 J APPL PHYS UT ISI:A1994NN73400041 ER PT Journal AU BROHL, K DINUNZIO, S SCHREIBER, F ZEIDLER, T ZABEL, H TI ANISOTROPY STUDIES OF AFM COUPLED MBE GROWN CO/CU(001) SUPERLATTICES SO JOURNAL OF APPLIED PHYSICS AB We have studied the anisotropy behavior of antiferromagnetically (AFM) coupled fcc Co/Cu(001) sandwiches and superlattices. Magneto-optical Kerr effect measurements on samples with Cu film thicknesses in the range of the second antiferromagnetic maximum reveal characteristic shapes of the hysteresis loops in close agreement with theoretical predictions. For the AFM coupled samples we infer antiparallel spin orientations in remanence perpendicular to the originally applied magnetic field direction. Changing the magnetic layer thickness and maintaining a constant thickness of the spacer completely alters the shape of the hysteresis loops. The loops of weakly coupled AFM layers show characteristic steps, indicative for a rather unusual nonsymmetric spin state. This behavior can be explained by the competing effects of anisotropy with the exchange coupling. TC 4 BP 6184 EP 6186 PG 3 JI J. Appl. Phys. PY 1994 PD MAY 15 VL 75 IS 10 PN 2A GA NN734 J9 J APPL PHYS UT ISI:A1994NN73400265 ER PT Journal AU BROHL, K ZEIDLER, T SCHREIBER, F SCHREYER, A ZABEL, H TI EVIDENCE FOR AN ANISOTROPY-INDUCED NONCOLLINEAR SPIN-STATE IN EXCHANGE-COUPLED CO/CU(001) SO JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS AB The magnetization behaviour of a Co/Cu/Co(001) sandwich has been studied by magneto-optical Kerr effect measurements. The sample was grown by molecular beam epitaxy onto a sapphire (11.2BAR) substrate with a Cu/Cr/Nb(001) buffer system. The copper layer had the form of a wedge with the thickness range chosen to be around the second region of antiferromagnetic exchange coupling. The hysteresis loops in the regime of weak antiferromagnetic coupling show characteristic steps, which can be explained by an anisotropy-induced non-collinear spin state. Indication for a similar behaviour is also found in the regime of strong antiferromagnetic coupling. This behaviour is explained by taking into account the competition between anisotropy, interlayer exchange coupling and external field energy. The nature of this metastable non-collinear magnetization state is in marked contrast to the biquadratic (90-degrees) exchange coupling which was discovered in Fe/Cr(001). TC 3 BP L1 EP L5 PG 5 JI J. Magn. Magn. Mater. PY 1994 PD FEB VL 130 IS 1-3 GA MZ821 J9 J MAGN MAGN MATER UT ISI:A1994MZ82100001 ER PT Journal AU DIENY, B RIBAS, R BARBARA, B TI NOVEL MAGNETIZATION PROCESSES IN FERRIMAGNETIC MULTILAYERS WITH RANDOM ANISOTROPY SO JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS AB We carried out a numerical study of magnetization processes in ferrimagnetic multilayers in the presence of pinning forces acting on one of the magnetic components. The multilayers consist of an alternation of two ferromagnetic materials (M and T) which are assumed antiferromagnetically coupled through the interfaces (as in Fe/Tb multilayers for instance). A random anisotropy field acts on the magnetization of material T. The reversal of the magnetization of the multilayers when the applied field is swept from positive saturation to negative saturation is characterized by a competition between coherent rotation and nucleation-propagation mechanisms. In this competition the rotational hysteresis induced by the random anisotropy on the magnetization of material T plays a crucial role. Very original features have been observed in the magnetization processes of these systems such as crossed hysteresis loops with a negative remanent magnetization. An overview of these magnetization processes below and above the compensation temperature is given in this paper. TC 2 BP 189 EP 196 PG 8 JI J. Magn. Magn. Mater. PY 1994 PD FEB VL 130 IS 1-3 GA MZ821 J9 J MAGN MAGN MATER UT ISI:A1994MZ82100025 ER PT Journal AU HEINRICH, B COCHRAN, JF TI ULTRATHIN METALLIC MAGNETIC-FILMS - MAGNETIC ANISOTROPIES AND EXCHANGE INTERACTIONS SO ADVANCES IN PHYSICS TC 206 BP 523 EP 639 PG 117 JI Adv. Phys. PY 1993 PD SEP-OCT VL 42 IS 5 GA MY735 J9 ADVAN PHYS UT ISI:A1993MY73500001 ER PT Journal AU BLOEMEN, PJH JOHNSON, MT VANDEVORST, MTH COEHOORN, R DEVRIES, JJ JUNGBLUT, R DESTEGGE, JA REINDERS, A DEJONGE, WJM TI MAGNETIC LAYER THICKNESS DEPENDENCE OF THE INTERLAYER EXCHANGE COUPLING IN (001) CO/CU/CO SO PHYSICAL REVIEW LETTERS AB A dependence of the strength of the antiferromagnetic coupling across Cu on the Co layer thickness has been observed in an epitaxial fcc (001) triple wedge sample containing two Co wedges and one Cu wedge. Our result is consistent with an oscillation period of 6-7 angstrom Co - a value that agrees with the period of 3.5 monolayers of Co derived from the extremal wave vector that spans the ellipsoidal hole pocket centered at the X point of the fcc Co spin-down Fermi surface. This shows that the interlayer exchange coupling does not just involve an interaction localized at the interfaces, but is a property of the sandwich as a whole. TC 100 BP 764 EP 767 PG 4 JI Phys. Rev. Lett. PY 1994 PD JAN 31 VL 72 IS 5 GA MU628 J9 PHYS REV LETT UT ISI:A1994MU62800044 ER PT Journal AU STAMPS, RL TI SPIN CONFIGURATIONS AND SPIN-WAVE EXCITATIONS IN EXCHANGE- COUPLED BILAYERS SO PHYSICAL REVIEW B AB The ground-state spin configuration of antiferromagnetically coupled ferromagnetic thin films is determined by competition between anisotropies, interlayer exchange, and the applied field. A theory for spin waves is presented where both exchange and dipolar interactions are accounted for and it is shown how dramatic changes in the spin-wave frequencies can be observed by carefully choosing the experimental geometry. Also, many details of the ground-state spin configuration can be obtained by studying the behavior of the spin-wave frequencies as functions of propagation direction and applied field strength in these geometries. The results are summarized from the point of view of possible light-scattering experiments. TC 21 BP 339 EP 347 PG 9 JI Phys. Rev. B PY 1994 PD JAN 1 VL 49 IS 1 GA MQ912 J9 PHYS REV B UT ISI:A1994MQ91200043 ER PT Journal AU CAMLEY, RE STAMPS, RL TI MAGNETIC MULTILAYERS - SPIN CONFIGURATIONS, EXCITATIONS AND GIANT MAGNETORESISTANCE SO JOURNAL OF PHYSICS-CONDENSED MATTER AB We discuss some of the fundamental properties unique to magnetic multilayers. Complex spin configurations are examined for many different systems and are shown to arise from a simple competition between exchange and Zeeman energies. The spin configurations found in multilayer systems determine macroscopic properties such as the static susceptibility and magnetization, and can lead to anomalous field and temperature behaviour. We also discuss the dynamic behaviour of magnetic multilayers. Emphasis is placed on spin waves in magnetic multilayers with canted spin configurations and the softening of modes at magnetic phase transitions. Furthermore we show that spin wave excitations provide a powerful method for studying exchange interactions and spin configurations. Finally, the phenomenon of giant magnetoresistance in magnetic multilayers, where the resistivity of the metallic structure can be changed by over 60% at room temperature, is discussed. Simple theoretical approaches are used to understand and predict the properties of the multilayer systems and comparisons between theory and experiment are stressed. TC 93 BP 3727 EP 3786 PG 60 JI J. Phys.-Condes. Matter PY 1993 PD JUN 7 VL 5 IS 23 GA LG297 J9 J PHYS-CONDENS MATTER UT ISI:A1993LG29700003 ER PT Journal AU BLAND, JAC BATESON, RD JOHNSON, NF BLUNDELL, SJ SPERIOSU, VS METIN, S GURNEY, BA PENFOLD, J TI MAGNETIC COUPLING IN FE/CR/FE SANDWICH STRUCTURES DIRECTLY OBSERVED BY POLARIZED NEUTRON REFLECTION SO JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS AB We have used polarised neutron reflection to directly determine the vector orientation of the individual Fe layer average magnetisations in an antiferromagnetically coupled 50angstromFe/15angstromCr/50angstromFe sandwich structure prepared by sputtering. The spin dependent neutron wave in the multilayer structure is represented by a two component spinor and the resulting reflected intensity is found to be highly sensitive to variations in the orientations of the layer- dependent magnetisation vectors, permitting the preferred orientation of the average magnetisation in each Fe layer to be studied. The saturated state is found to correspond to a uniform ferromagnetic alignment of the Fe layer magnetisations. At low field, we are able to assess the degree to which the magnetic alignment is fully antiparallel, and conclude that our results are consistent with the development of a multidomain structure. TC 6 BP 320 EP 324 PG 5 JI J. Magn. Magn. Mater. PY 1993 PD MAY VL 123 IS 3 GA LG402 J9 J MAGN MAGN MATER UT ISI:A1993LG40200014 ER PT Journal AU WATSON, ML DOYLE, WD FUJIWARA, H HOSSAIN, S TI THE ABSENCE OF GIANT MAGNETORESISTANCE ON ANTIFERROMAGNETICALLY COUPLED NIFE/CR MULTILAYERS SO JOURNAL OF APPLIED PHYSICS AB To further investigate the relationship between the giant magnetoresistance (GMR), anisotropic magnetoresistance (AMR), and antiferromagnetic (AFM) coupling found in magnetic multilayers we have deposited NiFe/Cr multilayers onto rectangular Coming 7059 glass substrates at ambient temperatures. Uniaxial anisotropy was induced by applying a 90 Oe field along the length of the substrate strips during deposition and in all cases a 50-100-angstrom-thick Cr underlayer was used. For Cr interfilms 9-12-angstrom thick, the multilayers were found to have hard axis saturation fields of 90-200 Oe and easy axis hysteresis loops which exhibit a complex behavior dependent on whether the multilayer is composed of an even or an odd number of NiFe films. Both of these effects result from AFM coupling of the NiFe films. The magnetoresistive (MR) behavior was also found to be complex and dependent on the number of NiFe films in the multilayer. A theoretical model based on coherent rotation and including AFM coupling between the NiFe films has been developed and both the hysteresis loops and MR of the multilayers calculated. From these calculations it has been found that, despite the existence of AFM coupling, the experimentally observed magnetoresistive behavior can be described using only AMR. Thus the existence of AFM coupling does not result in GMR NiFe/Cr multilayers. This is discussed in terms of spin filtering at the multilayer interfaces. TC 8 BP 5518 EP 5520 PG 3 JI J. Appl. Phys. PY 1993 PD MAY 15 VL 73 IS 10 PN 2A GA LD854 J9 J APPL PHYS UT ISI:A1993LD85400084 ER PT Journal AU WIGEN, PE ZHANG, Z ZHOU, L YE, M COWEN, JA TI THE DISPERSION-RELATION IN ANTIPARALLEL COUPLED FERROMAGNETIC- FILMS SO JOURNAL OF APPLIED PHYSICS AB The dispersion relation of the system with two identical magnetic layers antiparallel coupled is modified from the normal antiferromagnetic material as well as that of the single ferromagnetic layer. With the external field in the film plane parallel to the in-plane easy axis, three unique regions exist as the antiparallel, canted and saturation region. The resonance field of the acoustic mode shifts significantly compared with that of a noncoupled layer system if the magnetization is not saturated. No antiparallel state exists with the external field perpendicular to the film plane and a minimum frequency, omega = 2gammaH(E), is required to observe the acoustic resonance mode. In each orientation the optical mode exists at a field of 2H(E) higher than that of the acoustic mode in the saturation region. These calculations are very helpful to understand the unusual ferromagnetic resonance spectrum in the strong antiparallel coupled bilayer system being investigated in this lab. TC 7 BP 6338 EP 6340 PG 3 JI J. Appl. Phys. PY 1993 PD MAY 15 VL 73 IS 10 PN 2B GA LD865 J9 J APPL PHYS UT ISI:A1993LD86500072 ER PT Journal AU DABOO, C BLAND, JAC HICKEN, RJ IVES, AJR BAIRD, MJ WALKER, MJ TI A MAGNETOOPTIC TECHNIQUE FOR STUDYING MAGNETIZATION REVERSAL PROCESSES AND ANISOTROPIES APPLIED TO CO/CU/CO TRILAYER STRUCTURES SO JOURNAL OF APPLIED PHYSICS AB We report the magnetization reversal and magnetic anisotropy behavior of ultrathin Co/Cu(111)/Co(d(Cu) = 20 and 27 angstrom) trilayer structures prepared by MBE on a 500-angstrom Ge/GaAs(110) epilayer. We describe an arrangement in which the magnetization components parallel and perpendicular to the applied field are both determined from longitudinal MOKE measurements. For the samples examined, coherent rotation of the magnetization vector is observed when the magnetic field is applied along the hard in-plane anisotropy axis, with the magnitude of the magnetization vector constant and close to its bulk value. Results of micromagnetic calculations closely reproduce the observed parallel and perpendicular magnetization loops, and yield strong uniaxial magnetic anisotropies in both layers while the interlayer coupling appears to be absent or negligible in comparison with the anisotropy strengths. An absence of antiferromagnetic (AF) coupling has been observed previously [W. F. Egelhoff, Jr. and M. T. Kief, Phys. Rev. B 45, 7795 (1992)] in contrast to recent results, indicating that AF coupling [M. T. Johnson et al., Phys. Rev. Lett. 69, 969 (1992)] and GMR [D. Grieg et al., J. Magn. Magn. Mater. 110, L239 (1992)] can occur in Co/Cu(111)/Co structures grown by MBE, but these properties are sensitively dependent on growth conditions. The absence of coupling in our samples is attributed to the presence of a significant interface roughness induced by the Ge epilayer. The uniaxial anisotropies are assumed to arise from strain or defects induced in the film. TC 4 BP 6368 EP 6370 PG 3 JI J. Appl. Phys. PY 1993 PD MAY 15 VL 73 IS 10 PN 2B GA LD865 J9 J APPL PHYS UT ISI:A1993LD86500082 ER PT Journal AU DABOO, C BLAND, JAC HICKEN, RJ IVES, AJR BAIRD, MJ WALKER, MJ TI VECTORIAL MAGNETOMETRY WITH THE MAGNETOOPTIC KERR EFFECT APPLIED TO CO/CU/CO TRILAYER STRUCTURES SO PHYSICAL REVIEW B AB We describe an arrangement in which the magnetization components parallel and perpendicular to the applied field are both determined from longitudinal magneto-optic Kerr effect measurements. This arrangement differs from the usual procedures in that the same optical geometry is used but the magnet geometry altered. This leads to two magneto-optic signals which are directly comparable in magnitude thereby giving the in-plane magnetization vector directly. We show that it is of great value to study both in-plane magnetization vector components when studying coupled structures where significant anisotropies are also present. We discuss simulations which show that it is possible to accurately determine the coupling strength in such structures by examining the behavior of the component of magnetization perpendicular to the applied field in the vicinity of the hard in-plane anisotropy axis. We illustrate this technique by examining the magnetization and magnetic anisotropy behavior of ultrathin Co/Cu(111)/Co (d(Cu)=20 angstrom and 27 angstrom) trilayer structures prepared by molecular beam epitaxy, in which coherent rotation of the magnetization vector is observed when the magnetic field B is applied along the hard in-plane anisotropy axis, with the magnitude of the magnetization vector constant and close to its bulk value. Results of micromagnetic calculations closely reproduce the observed parallel and perpendicular magnetization loops, and yield strong uniaxial magnetic anisotropies in both layers, while the interlayer coupling appears to be absent or negligible in comparison with the anisotropy strengths. TC 20 BP 11852 EP 11859 PG 8 JI Phys. Rev. B PY 1993 PD MAY 1 VL 47 IS 18 GA LD189 J9 PHYS REV B UT ISI:A1993LD18900026 ER PT Journal AU BLOEMEN, PJH DEJONGE, WJM DONKERSLOOT, HC TI DETERMINATION OF THE FERROMAGNETIC COUPLING ACROSS PD BY MAGNETO-ATOMIC ENGINEERING SO JOURNAL OF APPLIED PHYSICS AB The ferromagnetic coupling across Pd interlayers has been determined from hysteresis loop measurements on perpendicular- magnetized multilayers of the type M3/8 Ru/M2/xPd/M1. Here M1, M2, and M3 denote magnetic layers consisting of (strongly ferromagnetically coupled) Co/Pd multilayers with perpendicular magnetic anisotropy: M1 = [3Co + 4 X (4Co + 6Pd)], M2 = [3Co + 4 X (4Co + 6Pd) + 7Co] and M3 = [20 X (6Pd + 4Co) + 3Co]. (The layer thicknesses are in angstrom.) The determination of the ferromagnetic coupling across the Pd interlayer with variable thickness x was enabled by pinning the second magnetic layer M2. This pinning was achieved by the relatively strong antiferromagnetic coupling (by the Ru layer) to the thickest magnetic layer M3. The hysteresis loops displayed a staircase behavior, with two or three steps (levels), depending on the strength of the ferromagnetic coupling. From the fields at which the steps occurred, the ferromagnetic coupling across Pd, as well as the antiferromagnetic coupling across the 8 angstrom Ru layer, were determined. A monotonic decrease of the former was observed from 0.17 mJ/m2 at 14 angstrom Pd to almost-equal- to 0.02 mJ/m2 at 20 angstrom Pd. TC 1 BP 4522 EP 4527 PG 6 JI J. Appl. Phys. PY 1993 PD MAY 1 VL 73 IS 9 GA LA320 J9 J APPL PHYS UT ISI:A1993LA32000060 ER PT Journal AU HEINRICH, B CELINSKI, Z COCHRAN, JF ARROTT, AS MYRTLE, K PURCELL, ST TI BILINEAR AND BIQUADRATIC EXCHANGE COUPLING IN BCC FE/CU/FE TRILAYERS - FERROMAGNETIC-RESONANCE AND SURFACE MAGNETOOPTICAL KERR-EFFECT STUDIES SO PHYSICAL REVIEW B AB Ferromagnetic-resonance (FMR) and surface magneto-optical Kerr- effect (SMOKE) studies of the exchange coupling in bcc Fe/Cu/Fe(001) structures are presented. It is shown that the interfaces in bcc Fe/Cu/Fe(001) trilayers grown on a Ag(001) single-crystal substrate can be significantly improved by choosing an appropriate growth procedure. Low-energy electron- diffraction data are presented, which show that the bcc Cu(001) overlayer follows a nearly perfect bcc lattice. The exchange coupling in bcc Fe/Cu/Fe trilayers was studied as a function of interlayer thickness ranging from 7 to 14 monolayers. Quantitative data from FMR and SMOKE measurements are compared. The interpretation of magnetization loops for Fe/Cu/Fe trilayers requires the simultaneous presence of bilinear and biquadratic exchange coupling between the magnetic layers. Computer calculations were used to determine the strength of the bilinear and biquadratic exchange couplings. It is shown that the strength of the biquadratic exchange coupling increases with increasing terrace width. The measured values of the bilinear and biquadratic exchange coupling were compared with a model recently proposed by Slonczewski, which treats the exchange coupling in trilayers with imperfect interfaces. Slonczewski's model was used to deconvolute the data to obtain the intrinsic behavior of the bilinear exchange coupling in bcc Fe/Cu/Fe(001) trilayers. It is shown that the exchange coupling unobscured by interface roughness exhibits a strong short- wavelength oscillatory behavior that is in agreement with recent first-principles band calculations. Composite Ag-Cu structures were also studied. The presence of a few atomic layers of Ag(001) added to the Cu layer rapidly decreases the exchange coupling. TC 50 BP 5077 EP 5089 PG 13 JI Phys. Rev. B PY 1993 PD MAR 1 VL 47 IS 9 GA KQ099 J9 PHYS REV B UT ISI:A1993KQ09900035 ER PT Journal AU BLOEMEN, PJH JOHNSON, MT DESTEGGE, JA DEJONGE, WJM TI ANTIFERROMAGNETIC COUPLING BETWEEN CO/NI MULTILAYERS WITH PERPENDICULAR MAGNETIZATION ACROSS MBE-GROWN CU(111) LAYERS SO JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS AB A clear oscillatory exchange coupling has been observed for an epitaxial (111) M1/Cu/M2 structure, grown by Molecular Beam Epitaxy (MBE) on a single crystal Cu(111) substrate. The magnetic layers M1 and M2 were designed to have perpendicular easy axis by using Co/Ni multilayers. The Cu layer was deposited in the form of a wedge. The magneto-optically measured hysteresis loops show, in the case of antiferromagnetic (AF) coupling, clear first-order spin-flip transitions between the saturated and antiparallel states. Signatures of a ferromagnetic or biquadratic component, observed earlier in loops of an AF coupled Co/Cu/Co(111) sandwich, were absent in the present loops. The absence of these signatures is believed to be a consequence of the relatively strong (perpendicular) uniaxial anisotropy of the present samples. TC 7 BP L315 EP L319 PG 5 JI J. Magn. Magn. Mater. PY 1992 PD OCT VL 116 IS 3 GA JZ592 J9 J MAGN MAGN MATER UT ISI:A1992JZ59200004 ER PT Journal AU NORTEMANN, FC STAMPS, RL CARRICO, AS CAMLEY, RE TI FINITE-SIZE EFFECTS ON SPIN CONFIGURATIONS IN ANTIFERROMAGNETICALLY COUPLED MULTILAYERS SO PHYSICAL REVIEW B AB Nonuniform canting states are found for multilayers of a finite size that are constructed from ferromagnetic films which are antiferromagnetically coupled. Our results are applicable to a wide variety of experimentally realizable systems such as Fe/Cr and Co/Ru. We find that at low fields, a twist in the ground- state configuration of the spins reduces the net Zeeman energy and is energetically favorable to the uniform canted state which has previously been assumed by most authors. At higher fields, the character of this twist changes and eventually leads to a state that is fully aligned along the direction of the applied magnetic field. A numerical self-consistent mean- field model is used to examine the properties of these states and a variational method is developed in order to obtain analytic expressions for the lengths and magnitudes of these twists. The deviations from the uniform spin-flop state at both high and low fields can be quite large and involve the entire sample. TC 30 BP 10847 EP 10853 PG 7 JI Phys. Rev. B PY 1992 PD NOV 1 VL 46 IS 17 GA JW976 J9 PHYS REV B UT ISI:A1992JW97600045 ER PT Journal AU KAMIJO, A IGARASHI, H TI MAGNETISM AND MAGNETORESISTANCE IN EPITAXIAL FE/CR(001) SUPERLATTICES SO JOURNAL OF APPLIED PHYSICS AB Epitaxial Fe/Cr(001) superlattices, having different topological interface roughnesses, were grown by the molecular beam epitaxy technique. The interface roughness was characterized by in situ reflection high-energy electron diffraction and ex situ scanning tunneling microscopy. The magnetic field (H) dependences for magnetization (M) and magnetoresistance (MR) have been discussed. Large topological interfacial roughness led to a substantial reduction in the MR ratio. In the case of superlattices with sufficiently small and similar topological interfacial roughnesses, the MR ratio decreased with lowering the superlattice growth temperature. M2 dependence for magnetoresistance, which was independent from the sample qualities, was found. TC 6 BP 3497 EP 3503 PG 7 JI J. Appl. Phys. PY 1992 PD OCT 15 VL 72 IS 8 GA JT986 J9 J APPL PHYS UT ISI:A1992JT98600038 ER PT Journal AU WATSON, ML WHITING, JSS CHAMBERS, A THOMPSON, SM TI STUDIES OF THE EFFECT OF INTERFACIAL INTERDIFFUSION ON THE COUPLING OF NIFE FILMS THROUGH A CHROMIUM INTERFILM SO JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS AB Interfacial interdiffusion in NiFe/Cr/NiFe trilayers prepared by molecular beam epitaxy (MBE) is promoted in a controlled manner by varying the deposition temperature of the interfilm. The resulting progressive removal of one of the sharp interfaces enables studies of the effect of the reduced electronic confinement of the interface. The films were structurally characterised-by Auger electron spectroscopy (AES) and reflection high energy electron diffraction (RHEED) and the magnetic properties investigated by ferromagnetic resonance (FMR) and with a vibrating sample magnetometer (VSM). Changes in the coupling were discovered between the films supporting different degrees of interdiffusion and on cooling some of the trilayers, coupling changes were also detected. TC 3 BP 97 EP 104 PG 8 JI J. Magn. Magn. Mater. PY 1992 PD JUL VL 113 IS 1-3 GA JJ493 J9 J MAGN MAGN MATER UT ISI:A1992JJ49300015 ER PT Journal AU JOHNSON, MT COEHOORN, R DEVRIES, JJ MCGEE, NWE DESTEGGE, JA BLOEMEN, PJH TI ORIENTATIONAL DEPENDENCE OF THE OSCILLATORY EXCHANGE INTERACTION IN CO/CU/CO SO PHYSICAL REVIEW LETTERS AB A strong oscillatory exchange coupling has been discovered in epitaxial (111) and (110) Co/Cu/Co sandwiches with wedge-shaped Cu layers, deposited by molecular-beam epitaxy (MBE) on single- crystal substrates. This finding proves the intrinsic nature of the strong antiferromagnetic coupling in (111)-textured sputtered Co/Cu multilayers. Combined with recent results on (100) Co/Cu/Co MBE-grown samples, it becomes evident that the nature of the oscillations in Co/Cu/Co depends markedly on growth direction, agreeing with predictions invoking the topology of the Fermi surface of the interlayer Cu. TC 121 BP 969 EP 972 PG 4 JI Phys. Rev. Lett. PY 1992 PD AUG 10 VL 69 IS 6 GA JJ328 J9 PHYS REV LETT UT ISI:A1992JJ32800027 ER PT Journal AU MARTINEZ, JL TI MAGNETIC-PROPERTIES OF 3D-METAL SUPERLATTICES AND MULTILAYERS - A NEUTRON-DIFFRACTION STUDY SO PHYSICA B AB Recent neutron diffraction results on the magnetic properties of Co-Cu, Fe-Cr, Fe-Ru and Mn-Ru superlattices, as well as Ag- Ni and Co-Cu multilayers are discussed. In all the cases, for a given thickness of the magnetic layer, the magnetic moments present long range in-plane ferromagnetic order. The coupling to the next magnetic layer through the non-magnetic intermediate metal is antiferromagnetic, with a strong dependence on the thickness of the intermediate metal layer. The coupling mechanism is discussed in comparison with thin film data. TC 1 BP 39 EP 42 PG 4 JI Physica B PY 1992 PD JUN VL 180 PN A GA JD723 J9 PHYSICA B UT ISI:A1992JD72300010 ER PT Journal AU OUNADJELA, K MULLER, D DINIA, A ARBAOUI, A PANISSOD, P SURAN, G TI PERPENDICULAR ANISOTROPY AND ANTIFERROMAGNETIC COUPLING IN CO/RU STRAINED SUPERLATTICES SO PHYSICAL REVIEW B AB Despite the large lattice mismatch (congruent-to 8%), we demonstrate the growth of epitaxially ordered Co/Ru superlattices consisting of hcp (0001) Co and Ru sublayers. For small Ru interlayer thickness, a large antiferromagnetic exchange coupling between the Co sublayers is observed that influences strongly the magnetization process, as the magnetization within Co sublayers can no longer be considered to be fully locked ferromagnetically. For small Co and Ru thicknesses, the magnetization is oriented along the film normal, while the adjacent Co layers are strongly coupled antiferromagnetically. For this peculiar magnetic structure, a first-order spin-flop transition from an antiferromagnetic state to a ferromagnetic canted state is observed and clearly revealed by use of a ferromagnetic-resonance technique. TC 33 BP 7768 EP 7771 PG 4 JI Phys. Rev. B PY 1992 PD APR 1 VL 45 IS 14 GA HN477 J9 PHYS REV B UT ISI:A1992HN47700018 ER PT Journal AU KOBLER, U WAGNER, K WIECHERS, R FUSS, A ZINN, W TI HIGHER-ORDER INTERACTION TERMS IN COUPLED FE/CR/FE SANDWICH STRUCTURES SO JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS AB From experimental studies of magnetization curves of Fe/Cr/Fe sandwich structures grown epitaxially on GaAs (100) substrates there is evidence for a cosine-square term in addition to the linear Heisenberg-like interlayer exchange interaction. The different dependences of both exchange mechanisms with the interlayer thickness are shown to result in thickness ranges where the biquadratic term even dominates the linear one which results in characteristic anomalies in the remagnetization behaviour. TC 28 BP 236 EP 244 PG 9 JI J. Magn. Magn. Mater. PY 1992 PD JAN VL 103 IS 3 GA HG242 J9 J MAGN MAGN MATER UT ISI:A1992HG24200004 ER PT Journal AU CHERIFI, K DUFOUR, C BAUER, P MARCHAL, G MANGIN, P TI EXPERIMENTAL MAGNETIC PHASE-DIAGRAM OF A GD/FE MULTILAYERED FERRIMAGNET SO PHYSICAL REVIEW B AB The experimental magnetic phase diagram of a Gd/Fe multilayer with compensation temperature is reported. Aligned and twisted states are shown to occur as predicted by theoretical simulations. The critical field for the aligned-to-twisted state transition is maximum at 4.2 K and goes to a minimum at the compensation temperature. The magnetic susceptibility is largest at the onset of the twisted state, with a maximum at the compensation temperature. The critical field for the aligned-to-twisted state transition increases when the thickness of the layers decreases. TC 29 BP 7733 EP 7736 PG 4 JI Phys. Rev. B PY 1991 PD OCT 1 VL 44 IS 14 GA GH808 J9 PHYS REV B UT ISI:A1991GH80800071 ER PT Journal AU DUFOUR, C CHERIFI, K BRUSON, A MARCHAL, G MANGIN, P TI CHARACTERIZATION OF THE GROWTH-PROCESS OF TB/FE MULTILAYERS BY ELECTRICAL-RESISTIVITY SO PHYSICA STATUS SOLIDI A-APPLIED RESEARCH AB Tb/Fe multilayers are obtained by vacuum evaporation on substrates kept at different temperatures (in the 90 to 420 K range). In order to characterize the structure of the terbium and iron layers, electrical resistivity measurements are performed during the deposition process. At low substrate temperature iron is first amorphous and then crystallizes at a critical thickness depending on the deposition temperature. At high substrate temperature, it forms an amorphous alloy with the rare-earth, then pure b.c.c. iron grows. Terbium shows a large resistivity due to the crystallinity of the layers. The results are consistent with Mossbauer spectroscopy and electron microscopy observations. TC 15 BP 561 EP 570 PG 10 JI Phys. Status Solidi A-Appl. Res. PY 1991 PD JUN 16 VL 125 IS 2 GA GG399 J9 PHYS STATUS SOLIDI A-APPL RES UT ISI:A1991GG39900016 ER PT Journal AU BAUER, P SAJIEDDINE, M DUFOUR, C CHERIFI, K MARCHAL, G MANGIN, P TI DIRECT EVIDENCE OF THE TWISTED STATE IN FERRIMAGNET GD/FE MULTILAYERS BY MOSSBAUER-SPECTROSCOPY SO EUROPHYSICS LETTERS AB Magnetic texture of a Gd(84 angstrom)/Fe(42 angstrom) multilayered film has been investigated through Fe-57 Mossbauer spectroscopy by using a 45-degrees transmission geometry. The aligned and twisted states expected from simulations have been observed microscopically. The canting angles in the twisted state have been determined. TC 14 BP 307 EP 312 PG 6 JI Europhys. Lett. PY 1991 PD SEP 14 VL 16 IS 3 GA GF634 J9 EUROPHYS LETT UT ISI:A1991GF63400015 ER PT Journal AU BARNAS, J GRUNBERG, P TI ON THE STATIC MAGNETIZATION OF DOUBLE FERROMAGNETIC LAYERS WITH ANTIFERROMAGNETIC INTER-LAYER COUPLING IN AN EXTERNAL MAGNETIC- FIELD SO JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS AB The equilibrium static magnetization of double-layer structures in an external magnetic field is considered in the framework of the continuum approximation. The two ferromagnetic layers are assumed to be coupled antiferromagnetically across a thin interlayer. In a general case a twisted ordering occurs. The conditions for the rigid approximation to be valid are also discussed. TC 4 BP 57 EP 59 PG 3 JI J. Magn. Magn. Mater. PY 1991 PD JUL VL 98 IS 1-2 GA GA324 J9 J MAGN MAGN MATER UT ISI:A1991GA32400011 ER PT Journal AU WANG, XZ GE, YC ZHANG, Z TI PROPERTIES OF A SUPERLATTICE COMPOSED OF IDENTICAL FERROMAGNETIC-FILMS WITH ANTIFERROMAGNETIC INTERFACIAL COUPLING SO JOURNAL OF PHYSICS-CONDENSED MATTER AB We present theoretical studies of the magnetization, phase transition and twist angles of a superlattice composed of identical ferromagnetic films with antiferromagnetic coupling at the interfaces. The numerical results show there are some interesting properties of the superlattice. (i) There is a plateau on the magnetization-temperature curve for the period P = 4, and the curve has a peak at a definite temperature for P > 4 and a suitable external field. (ii) For a given external field and interfacial-coupling parameter the twist angles are sensitive to temperature, and the phase transition temperature from the twist state to the spin-parallel state does not change monotonically with the period of the superlattice. Some of the theoretical results are in agreement with the experimental results qualitatively. TC 3 BP 5107 EP 5114 PG 8 JI J. Phys.-Condes. Matter PY 1991 PD JUL 8 VL 3 IS 27 GA FW633 J9 J PHYS-CONDENS MATTER UT ISI:A1991FW63300003 ER PT Journal AU MARTINEZ, JL CEBOLLADA, A GALLEGO, JM DEMIGUEL, JJ OCAL, C MIRANDA, R FERRER, S FILLION, G REBOUILLAT, JP TI NEUTRON-DIFFRACTION STUDY ON THE FIELD-DEPENDENT MAGNETIC- ORDERING IN CO-CU SUPERLATTICES SO JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS AB We have studied Co-Cu single crystal superlattices by neutron diffraction and bulk magnetization measurements. Special care was paid to the proper orientation of the sample for the magnetization experiments, in order to distinguish between in- plane anisotropies. Neutron diffraction data shows a pattern from the new superstructure (periodicity LAMBDA-SL), as well as a second diffraction pattern of magnetic origin with 2 LAMBDA- SL periodicity. The antiferromagnetic (AF) ordering was confirmed by polarized neutron diffraction. There is a peculiar dependence on the applied external field. At moderated magnetic fields (6-8 kOe), the AF alignment is reversed to ferromagnetic. For lower magnetic fields, there is a complicated magnetic behavior, with strong competition between in-plane anisotropies and exchange coupling energy, which produce intermedium magnetic orderings. TC 7 BP 89 EP 94 PG 6 JI J. Magn. Magn. Mater. PY 1991 PD FEB VL 93 GA FP221 J9 J MAGN MAGN MATER UT ISI:A1991FP22100017 ER PT Journal AU SCHMIDT, W TI POINTS OF PHASE-TRANSITIONS IN THE MAGNETIZATION CURVE OF FERROMAGNETIC BILAYERS WITH ANTIFERROMAGNETIC COUPLING SO JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS AB Phase diagrams in a form of a dc field vs. interlayer coupling or anisotropy constant are calculated for a double bcc ferromagnetic Fe film with (100) surface. Phase diagrams are used to find the interlayer coupling from literature data. TC 1 BP 418 EP 420 PG 3 JI J. Magn. Magn. Mater. PY 1991 PD FEB VL 93 GA FP221 J9 J MAGN MAGN MATER UT ISI:A1991FP22100081 ER PT Journal AU WANG, XZ TI TEMPERATURE AND FIELD-DEPENDENCE OF MAGNETIZATION OF SUPERLATTICES WITH ANTIFERROMAGNETIC COUPLING SO PHYSICS LETTERS A AB We present a theoretical study of the magnetisation of a superlattice composed of identical ferromagnetic films with antiferromagnetic coupling at the interfaces. The numerical results show that there are some interesting properties of the superlattice. For s = 7/2 and R(= J(FF)/J(F)) = 0.082, the theoretical magnetisation-temperature curves agree with those obtained in the experiment with the superlattice (Gd10-Y10)225 qualitatively. TC 4 BP 425 EP 428 PG 4 JI Phys. Lett. A PY 1991 PD APR 15 VL 154 IS 7-8 GA FH907 J9 PHYS LETT A UT ISI:A1991FH90700022 ER PT Journal AU FOLKERTS, W TI CALCULATED MAGNETIC PHASE-DIAGRAMS AND MAGNETORESISTANCE CURVES FOR AN ANTIFERROMAGNETICALLY COUPLED MULTILAYER SYSTEM SO JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS AB The total energy of an antiferromagnetically coupled multilayer system is considered as a function of anisotropy symmetry and direction of an applied field. The possible relative orientations of the magnetizations in adjacent layers are expressed in magnetic phase diagrams. From these diagrams the possible magnetoresistance curves in Fe/Cr and similar systems can be derived. Using the diagrams the magnitude of the coupling can be derived easily from experimental magnetoresistance curves. TC 45 BP 302 EP 310 PG 9 JI J. Magn. Magn. Mater. PY 1991 PD MAR VL 94 IS 3 GA FF804 J9 J MAGN MAGN MATER UT ISI:A1991FF80400009 ER PT Journal AU STOEFFLER, D GAUTIER, F TI ELECTRONIC-STRUCTURE, MAGNETIC ORDER AND INTERLAYER MAGNETIC COUPLINGS IN METALLIC SUPERLATTICES SO PROGRESS OF THEORETICAL PHYSICS SUPPLEMENT AB The general trends for the electronic structure of perfect model superlattices A(m)B(n) are calculated using a real-space tight-binding model. The magnetic moments distribution and the interlayer magnetic couplings between ferromagnetic layers A(m) (A = Fe or Co) coupled by non-magnetic (B = V or Ru), nearly ferromagnetic (B = Pd) or antiferromagnetic (B = Cr) spacer layers B(n) are obtained as a function of the spacer thickness n. In a first part, we present the model we used for the calculation and the crystallographic structure of the considered superlattices (Fe/V, Fe/Cr, Co/Ru and Co/Pd). These considerations will be applied to the non-magnetic and nearly ferromagnetic cases to derive general trends for the magnetic interlayers couplings. In a second part, we apply the method we presented previously to the superlattices with an antiferromagnetic spacer (Fe3Cr(n)). Using first a "d" band calculation we show that the interlayer coupling energy can be understood in terms of a strong interfacial antiferromagnetic coupling and of a constrained magnetic wall in the Cr layer giving a rapidly oscillating coupling energy. An extension of the previous calculation taking into account the "spd" hybridization does not affect the previous conclusion. Finally we examine the distribution of magnetic moments and the stability of tilted antiferromagnetic Cr layers and we find that this magnetic structure is nearly degenerate with the collinear antiferromagnetic arrangement. TC 0 BP 139 EP 157 PG 19 JI Prog. Theor. Phys. Suppl. PY 1990 IS 101 GA FE058 J9 PROG THEOR PHYS SUPPL UT ISI:A1990FE05800008 ER PT Journal AU LACROIX, C DIENY, B GAVIGAN, JP GIVORD, D TI INTERLAYER COUPLING IN [3D FERROMAGNETIC NON-MAGNETIC]N MULTILAYERS SO THIN SOLID FILMS AB In the field of research on magnetic thin films, interest is rapidly developing in epitaxially grown sandwiches and multilayers because of the multitude of novel magnetic properties which such systems exhibit and because of the possibility they offer for studying certain aspects of fundamental magnetism in a well-controlled manner. One such interesting phenomenon currently under study is the coupling of magnetic layers in metallic superlattices made up of magnetic 3d elements (iron, nickel, cobalt) intercalated with non- magnetic layers. This coupling is found to be antiferromagnetic when the non-magnetic layer is copper or chromium, whereas it would seem to be ferromagnetic in all other cases. Such coupling has been discussed by a number of researchers in terms of Ruderman-Kittel-Kasuya-Yoshida (RKKY) and dipolar interactions but no satisfactory explanation has yet been proposed which gives a full account of the observed behaviour. On simply considering the magnetic response of the non-magnetic layer, ferromagnetic interlayer coupling is predicted for elements such as palladium which are close to the Stoner criterion. Far from the Stoner criterion (copper, gold etc.), a more detailed investigation of the magnetic energy is necessary. In this paper, we propose a novel discussion of the coupling; the magnetic energy due to the hybridization between the magnetic and non-magnetic 0ayers is calculated by a perturbation treatment. Several energy terms are obtained, some of which describe oscillating RKKY-type interactions while others are found to be analogous to antiferromagnetic superexchange interactions in insulators, and may be dominant. TC 4 BP 877 EP 885 PG 9 JI Thin Solid Films PY 1990 PD DEC 15 VL 193 IS 1-2 GA EQ610 J9 THIN SOLID FILMS UT ISI:A1990EQ61000035 ER PT Journal AU DIENY, B GAVIGAN, JP REBOUILLAT, JP TI MAGNETIZATION PROCESSES, HYSTERESIS AND FINITE-SIZE EFFECTS IN MODEL MULTILAYER SYSTEMS OF CUBIC OR UNIAXIAL ANISOTROPY WITH ANTIFERROMAGNETIC COUPLING BETWEEN ADJACENT FERROMAGNETIC LAYERS SO JOURNAL OF PHYSICS-CONDENSED MATTER TC 78 BP 159 EP 185 PG 27 JI J. Phys.-Condes. Matter PY 1990 PD JAN 8 VL 2 IS 1 GA CG807 J9 J PHYS-CONDENS MATTER UT ISI:A1990CG80700013 ER PT Journal AU DIENY, B GAVIGAN, JP TI MINIMUM ENERGY VERSUS METASTABLE MAGNETIZATION PROCESSES IN ANTIFERROMAGNETICALLY COUPLED FERROMAGNETIC MULTILAYERS SO JOURNAL OF PHYSICS-CONDENSED MATTER TC 43 BP 187 EP 194 PG 8 JI J. Phys.-Condes. Matter PY 1990 PD JAN 8 VL 2 IS 1 GA CG807 J9 J PHYS-CONDENS MATTER UT ISI:A1990CG80700014 ER