Articles

Those articles were collected on 2000.02.23

No comment: means not processed (not interesting).

SCI CDE with Abstracts  (Jan 99 - Nov 99)       (D4.1)

• Record 1 of 1. Process status: First glance (interesting).
  Title: Magnetic Dichroism and Spin-Resolved Photoemission from Rough Interfaces
  Authors: Uzdin-VM Knabben-D Hillebrecht-FU Kisker-E
  Full source: PHYSICAL REVIEW B-CONDENSED MATTER 1999, Vol 59, Iss 2, pp 1214-1222
  Abstract: The magnetic structure of ultrathin Cr films on Fe is analyzed by taking into account the roughness of the surface and of the interface. An algorithm for the epitaxial growth of the film simulates the near-surface structure, and the magnetic moment distribution is calculated self-consistently in a periodic Anderson model. For rough interfaces we find that the layered antiferromagnetic structure of the Cr adlayer is quenched. Within this model we determine the spin polarization and the value of the magnetic linear dichroism to be expected in angle-resolved photoemission. Comparing with experimental data it is concluded that Cr grows on the Fe(001) in a Stranski-Kastranoff mode. We propose an explanation based on the confinement of the itinerant electrons within the Cr islands on the Fe substrate. [S0163-1829(99)13801-3].
  SCI CDE with Abstracts (Jan 99 - Nov 99) (D4.1)
  
• Record 1 of 7. Process status: Printed. Readed (3 pages). This article is about surface roughness and its effects (no hyperfine distribution given).
  Title: Fe/Cr Interface Magnetism in the External Magnetic-Field
  Authors: Uzdin-VM Yartseva-NS
  Full source: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 1999, Vol 203, Iss NSI, pp 280-282
  Abstract: A method of self-consistent calculation of magnetic ordering in low-dimensional metallic structures in the presence of an external magnetic held is developed on the basis of periodic Anderson model. Multitude of self-consistent solutions for the magnetic moments distribution in interface region leads to a hysteresis-like dependence of the average magnetic moment on value of the applied held. The shape of hysteresis loop calculated individually for Fe;and for Cr atoms changes significantly depending on the structure of the interface region. (C) 1999 Elsevier Science B.V. All rights reserved.
  
• The `epitaxy' porgram, mentioned in lot of Uzdin articles: (state: Printed, converted to ps.)
  Title: Modeling of the magnetic properties of the Cr-Fe interface
  Also in ps.gz

       A. K. Kazansky 
       Institute of Physics, The University of St. Petersburg, St. Petersburg, 198904, Russia
  
       V. M. Uzdin 
       Institute of Chemistry, The University of St. Petersburg, Universitetskij pr. 2, St. Petersburg, 198904, Russia
  
  (Received 9 June 1995) 
  

  A method of self-consistent determination of magnetic ordering in rough Fe-Cr interfaces is developed. It comprises two basic algorithms. The first algorithm is the EPITAXY routine, which allows one to simulate the structure of the Fe-Cr interfaces. The EPITAXY algorithm works in two variants. One of them creates relatively regular structures while the second variant generates quite irregular interfaces. The second algorithm provides a routine for determination of the magnetic ordering in a spatially inhomogeneous structure. For sets of the interfaces, constructed with the EPITAXY algorithm and comprising 30 configurations, self-consistent calculations of the magnetic properties of the system are performed. This allows us to obtain the average physical quantities of the interface and its dependence on the coverage parameter zeta with a reasonable accuracy. It is shown that low coverages of Cr upon the Fe vicinal surface cause a decrease in the average magnetic moment of the interface iron atoms. The influence of surface roughness on the smoothing of the average magnetic-moment oscillations with surface coverage is demonstrated.
  Physical Review B 52, 9477-9485 (1995)
• Record 2 of 7. (Not important)
  Title: Phase-Shift of Exchange Coupling Oscilations in Magnetic Multilayers
  Authors: Uzdin-VM Yartseva-NS Adamowicz-L
  Full source: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 1999, Vol 203, Iss NSI, pp 283-285
  Abstract: The origin of phase shifts in the oscillatory behaviour of exchange coupling (EC) of Co/Ru/CO and Co/Cu/Co trillayers with an addition of Ag impurities into the Co layer is explained within the framework of a quantum-well (QW) model. It is shown that Ag impurities induce the shift of the Fermi level relative to the bottom of the band and allow the observation of short-range oscillations of the EC. This is in contrast to the studies involving the increase of the layer thickness where only the long-range period is observed due to ''aliasing'' effect. On the basis of the simplified infinite QW-theory the difference between phase shift in symmetrical and asymmetrical trilayers is analysed. (C) 1999 Elsevier Science B.V. All rights reserved.
  
• Record 3 of 7.
  Title: Noncollinear Magnetic-Structure of Fe Cr Interfaces
  Authors: Uzdin-VM Mokrani-A Demangeat-C Yartseva-NS
  Full source: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 1999, Vol 199, Iss JUN, pp 471-473
  Abstract: A new method based on the periodic Anderson model is developed for a vector description of the magnetic moments near a stepped Fe/Cr interface. The method allows one to perform self-consistent calculations of local magnetic moment and d-electron numbers on a given atomic site for different orientations of the moment relative to the quantization axis. The self-consistent solution with minimal energy on a site under consideration is used to perform the calculation for the next step. In this approach the noncollinear magnetic structure for stepped Fe/Cr superlattices is obtained. The ground state is always noncollinear and the angle between magnetic moments of Fe layers depends on the thickness of the Cr and Fe layers. (C) 1999 Elsevier Science B.V. All rights reserved.
  
• Record 4 of 7.
  Title: Structure of Cr Overlayers on Fe Surfaces - A New Approach for the Interpretation of Spin-Resolved Photoemission and Magnetic Dichroism Spectra
  Authors: Uzdin-VM Knabben-D Hillebrecht-FU Kisker-E
  Full source: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 1999, Vol 199, Iss JUN, pp 680-682
  Abstract: Results of investigations of Cr overlayers on Fe surfaces by magnetic linear dichroism in the angular distribution and spin-resolved cure level photoemission are analysed within the framework of a new model approach. It includes a special algorithm for modelling epitaxial growth of overlayers with different roughness together with self-consistent calculations of the magnetic moment distribution within a Periodic Anderson Model. On this basis the value of the magnetic dichroism and the spin polarisation in photoemission as functions of the Cr coverage can be modelled also For rough surfaces. The comparison of experimental spectra and theoretical coverage dependencies obtained for the different surface roughnesses leads to conclusions about the microscopic structure of Cr overlayers. (C) 1999 Elsevier Science B.V. All rights reserved.
  
• Record 5 of 7.
  Title: Noncollinear Magnetism of Fe Cr Films and Multilayers
  Authors: Uzdin-VM Yartseva-NS Yartsev-SV
  Full source: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 1999, Vol 197, Iss MAY, pp 70-72
  Abstract: The noncollinear magnetic structure of Fe overlayers on the stepped Cr substrate is calculated within the framework of a model Hamiltonian approach. Different noncollinear solutions are found by choosing the initial state for the self-consistency procedure. It is shown that for the stepped Fe/Cr interface the ground slate is noncollinear and the distribution of magnetic moment directions is not uniform in both the Fe and Cr layers. The dependence of the angle between the average moment of the Fe overlayer and the average moment of different Cr layers on the thickness of Fe coverage is obtained. (C) 1999 Elsevier Science B.V. All rights reserved.
  
• Record 6 of 7.
  Title: Quantum-Well States in Magnetic Multilayers and Non-Poisson Islands Formation During Epitaxial-Growth
  Authors: Uzdin-VM
  Full source: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 1999, Vol 197, Iss MAY, pp 85-87
  Abstract: Mechanism, responsible for the non-Poisson growth of islands of metal on metal substrate is suggested. It is connected with confinement of the electrons with one spin projection inside of the quantum wells (QW) formed by islands. Oscillations of the energy of these electrons with width of the wells lead to the suppression of the formation of islands with definite thickness. This effect is especially important for the submonolayer coverage and for the initial phase of epitaxial process. Analogy between QW-theory for the oscillations of exchange coupling in metallic magnetic multilayers and the theory of non-Poisson islands formation is discussed. (C) 1999 Elsevier Science B.V. All rights reserved.
  
• Record 7 of 7.
  Title: Magnetic Dichroism and Spin-Resolved Photoemission from Rough Interfaces
  Authors: Uzdin-VM Knabben-D Hillebrecht-FU Kisker-E
  Full source: PHYSICAL REVIEW B-CONDENSED MATTER 1999, Vol 59, Iss 2, pp 1214-1222
  Abstract: The magnetic structure of ultrathin Cr films on Fe is analyzed by taking into account the roughness of the surface and of the interface. An algorithm for the epitaxial growth of the film simulates the near-surface structure, and the magnetic moment distribution is calculated self-consistently in a periodic Anderson model. For rough interfaces we find that the layered antiferromagnetic structure of the Cr adlayer is quenched. Within this model we determine the spin polarization and the value of the magnetic linear dichroism to be expected in angle-resolved photoemission. Comparing with experimental data it is concluded that Cr grows on the Fe(001) in a Stranski-Kastranoff mode. We propose an explanation based on the confinement of the itinerant electrons within the Cr islands on the Fe substrate. [S0163-1829(99)13801-3].
  SCI CDE with Abstracts (Jan 99 - Nov 99) (D4.1)
  
• Record 4 of 4. State:First glance, found Fe/Cr CEMS data and reference. Pages 1-5, 16-18 printed. -> Must look for the referred journals.
  Title: Mossbauer-Effect Studies of Multilayers and Interfaces
  Authors: Shinjo-T Keune-W
  Full source: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 1999, Vol 200, Iss 1-3, pp 598-615
  Abstract: The usefulness of Mossbauer spectroscopy for the investigation of magnetic multilayer systems is described. By applying Fe-57 Mossbauer spectroscopy, the behavior of ultrathin magnetic layers, such as FCC-like Fe films on Cu(0 0 1). is studied. Position-specified (depth-selective) information is available by preparing samples in which monatomic Fe-57 probe layers are placed at specific vertical positions, e.g. at interfaces or at the surface. As demonstrated for egitaxial chemically ordered Fe50Pt50 alloy films and polycrystalline nanostructured Tb/Fe multilayers, the Fe-spin structure can be determined directly, and a site-selective Fe-specific magnetic hysteresis loop can be traced in very-highcoercivity materials. For the studies of non-magnetic layers, on the other hand, hyperfine field observations by Au-197 and Sn-119 probes are worthwhile. Spin polarizations in Au layers penetrating from neighboring ferromagnetic 3D layers are estimated from Au-197 Mossbauer spectra and are also studied by inserted Sn-119 probes in Au/3D multilayers. In the Sn spectra for Cr/Sn multilayers, it was found that remarkably large spin polarization is penetrating into Sn layers from a contacting Cr layer, which suggests that Cr atoms in the surface layer have a ferromagnetic alignment. (C) 1999 Elsevier Science B.V. All rights reserved.
  Articles found to Shinjo's:
  • State: No Fe/Cr data, but interesting Fe-57/V and discussion. (First glance) -> reference to Fe/Cr CEMS measurement.
    Title: Structure and magnetism of Fe mono- and multi-layer systems as seen by conversion electron Mössbauer spectroscopy at atomic scale
    Author: Marek Przybylski
    Solid State Physics Department, Faculty of Physics and Nuclear Techniques, University of Mining and Metallurgy, al. Mickiewicza
    30, 30-059 Kraków, Poland
    Full source: Hyperfine Interactions 113 (1998) 1-4 (Applications of the Mössbauer Effect (ICAME '97) )
    Abstract: The characteristic magnetic phenomena of ultrathin films are attributed to their reduced dimensionality and increased importance of the interfacial properties originated at their boundaries. The loss of nearest neighbor interactions at the interfaces, band hybridization, expansion or contraction of the atomic spacing occur, resulting in local changes of the energy band structure. Recent technical developments make it now possible to grow ultrathin films in a strictly layer-by-layer mode and to produce large areas of flat surfaces. Nevertheless, small structural perturbations in the local atomic configuration can still exist and result in significant changes of the global magnetic properties. Conversion Electron Mössbauer Spectroscopy (CEMS) determines the hyperfine interaction parameters which are sensitive to the arrangement at the atomic scale. In particular, depth selectivity at a monolayer level has been achieved in Fe films with one atomic layer replaced by the Mössbauer isotope 57Fe.

    This contribution reviews the experimental work on magnetic phenomena of bcc, fcc and hcp Fe ultrathin films (including monolayer and multilayer structures), epitaxially grown by condensation from molecular beam under ultrahigh vacuum conditions. Since the structural and magnetic information can be achieved by using one method only, Mössbauer spectroscopy is pointed out as being an extremely effective and convenient tool for such purposes.

  
  SCI CDE with Abstracts (Jan 99 - Nov 99) (D4.1)
  
• Record 1 of 4.
  Title: Spin-Density-Wave Magnetism in Cr Studied by Perturbed-Angular-Correlation Spectroscopy
  Authors: Meersschaut-J Dekoster-J Demuynck-S Cottenier-S Swinnen-B Rots-M
  Full source: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 1999, Vol 199, Iss JUN, pp 641-643
  Abstract: We compare the results obtained by the perturbed angular correlation (PAC) technique with data obtained from the same samples by neutron diffraction experiments. We report on the study of a 250 nm thick Cr film and an Fe/Cr (25 nm) multilayer grown on Nb/Al2O3 (1 1 0 2). The chromium film orders below T-N = 330 K as a AF(2) SDW with the spins out-of-plane, while the Cr in the Fe/Cr multilayer orders as an AF(1) SDW with the spins in-plane. In these samples, we no observe a minority volume fraction in the AF(0) phase, stable up to at least 400 K. These results validate PAC as a complementary approach towards the study of the Cr magnetic ordering in thin films and Fe/Cr multilayers. (C) 1999 Elsevier Science B.V. All rights reserved.
  
• Record 2 of 4.
  Title: The Effect of Interfacial Regions on the Giant Magnetoresistance in as-Grown and Annealed Fe/Cr Mlfs
  Authors: Ho-EM Petfordlong-AK Cerezo-A
  Full source: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 1999, Vol 192, Iss 3, pp 431-442
  Abstract: The influence of microstructure, in particular at the Fe/Cr interfaces on the giant magnetoresistance of both as-grown and annealed Fe/Cr multilayer films (MLFs) has been studied. The giant magnetoresistance varies with the spin-dependent resistivity, but the spin-independent resistivity was found to have a much greater effect on the magnitude of the giant magnetoresistance. A simple model was devised to determine the thickness t(mixed) of the interfacial region across which the composition changed from pure Fe to pure Cr. The morphology of the interfaces was found to have a large influence on the magnitude of the giant magnetoresistance, and for a very diffused interface i.e. a large t(mixed), the giant magnetoresistance effect was suppressed. The optimum annealing condition was at a temperature of 300 degrees C for 1 h, with changes in giant magnetoresistance being largely due to a decrease in the spin-independent resistivity upon annealing. (C) 1999 Elsevier Science B.V. All rights reserved.
  
• Record 3 of 4.
  Title: Magnetic Effect in Multilayer Fe/Cr Films
  Authors: Santos-VC Fernandes-AAR
  Full source: JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS 1999, Vol 10, Iss 1, pp 67-70
  Abstract: Ferromagnetic resonance measurements on different Fe/Cr multilayer samples with the same thickness of the spacing Cr layers suggest that these multilayers have a different magnetic behavior depending on the thickness of the active Fe layers. In this work we show that the change of magnetic behavior from bulk mode to surface mode is observed only when the thickness of the Fe layers is less than 4 nm. This is attributed to the Fe layer thickness and to the relative thickness of the magnetic and non-magnetic layers. (C) 1999 Kluwer Academic Publishers.
  
• Record 4 of 4. NB: We have a printed copy somewhere...? Download???? (Or not...) Cud be interesting for surface spin-flop.
  Title: Low-Frequency Dynamics in an Antiferromagnetic Superlattice
  Authors: Papanicolaou-N
  Full source: JOURNAL OF PHYSICS-CONDENSED MATTER 1999, Vol 11, Iss 1, pp 59-79
  Abstract: We present a theoretical study of the surface spin-flop transition which occurs in Fe/Cr multilayer films. The low-frequency response is effectively reduced to the dynamics of an antiferromagnetic discrete sine-Gordon equation due to the strong demagnetizing field created by out-of-plane fluctuations. We thus carry out a detailed calculation of dynamic susceptibilities which confirms and completes earlier theoretical work, and may suggest further experimental investigation of some of the more intricate aspects of this subject.
  SCI CDE with Abstracts (Jan 99 - Nov 99) (D4.1)
  
• Record 1 of 10. :Nice graphs and theory. Calculated field distribution, but only on graph, no data. (Should be looked at again!).
  Authors: Amalou-F Benakki-M Mokrani-A Demangeat-C
  Title: Surface Dependence of the Magnetic Configurations of the Ordered B2Fecr Alloy
  Full source: EUROPEAN PHYSICAL JOURNAL B 1999, Vol 9, Iss 1, pp 149-157
  Abstract: Tight-binding linear muffin tin orbitals calculations with generalized gradient approximation were carried out for the magnetic configurations at the surface of the ferromagnetic ordered B2 FeCr alloys. For both (001) and (111) crystallographic phases, non ferromagnetic configurations are shown to be more stable than the ferromagnetic configuration of the bulk alloy. For (001) surface we display a c(2 x 2) ground state for either Cr or Fe at the surface. For Cr top layer the magnetic moments are 700% larger than in the bulk B2 FeCr while they are slightly enhanced for Fe top layer. For (111) surface an antiferromagnetic coupling between surface and subsurface is always obtained i.e. for either Fe or Cr at the surface. This change of coupling between Fe and Cr (from ferromagnetic to antiferromagnetic) is expected to be fundamental to any explanation of the experimental results obtained for the interface alloying at the Fe/Cr interfaces.
• Record 2 of 10.
  Authors: Rho-TH Kwon-YS Hong-SC Lee-JI
  Title: Electronic and Magnetic-Properties of Fe Monolayer on Cr(110)
  Full source: IEEE TRANSACTIONS ON MAGNETICS 1999, Vol 35, Iss 5, pp 3061-3063
  Abstract: The electronic structure and the magnetism of Fe monolayer (ML) on Cr(110) are investigated by means of the all-electron full-potential linearized augmented plan-wave (FLAPW) method, based on the local density approximation (LDA), with a single slab approach. To investigate the magnetic structure we assumed three possible magnetic interlayer couplings: (i) a ferromagnetic Fe ML on an inplane antiferromagnetic (IAF) Cr(110) surface [FM Fe/IAF Cr(110)]; (ii) a layer antiferromagnetic (LAF) couping between adjacent layers [LAF Fe/Cr(110)]; (iii) an in-plane antiferromagnetic (IAF) coupling [IAF Fe/Cr(110)]. From total energy calculations FM Fe/IAF Cr(110) is found to be more stable by 9 meV and 550 meV than those of LAF Fe/Cr(110) and IAF Fe/Cr(110), respectively. It is found that the magnetic moments of Fe in FM Fe/IAF Cr(110), LAF Fe/Cr(110), and IAF Fe/Cr(110) are 2.23 mu(B), 2.22 mu(B), and 1.75 mu(B), respectively, which are comparable to the calculated value (2.22 mu(B)) Of bulk Fe. Meanwhile, the magnetic moments at the subsurfaces Cr(S-1) are 0.20 mu(B), 0.03 mu(B), and 0.43 mu(B) in FM Fe/IAF Cr(110), LAF Fe/Cr(110), and IAF Fe/Cr(110), respectively, which are significantly reduced compared to the calculated value (0.59 mu(B)) of bulk Cr. The work functions of FM Fe/IAF Cr(110), LAF Fe/Cr(110), and IAF Fe/Cr(110) are calculated to be 5.46 eV, 5.46 eV, and 5.62 eV, respectively.
• Record 3 of 10.
  Authors: You-CY Sowers-CH Inomata-A Jiang-JS Bader-SD Koelling-DD
  Title: Oscillation Period of the Interlayer Coupling for Epitaxial Fe/Cr1-Xvx(100) and Fe/Cr1-Xvx(211) Superlattices
  Full source: JOURNAL OF APPLIED PHYSICS 1999, Vol 85, Iss 8, pp 5889-5891
  Language: English
  Document type: Article
  IDS/Book No.: 188NF
  No. Related Records: 20
  No. cited references: 15
  Addresses: ARGONNE-NATL-LAB, DIV MAT SCI, 9700 S CASS AVE, ARGONNE, IL 60439, USA
  KeyWords Plus: FE/CR MULTILAYERS; GIANT MAGNETORESISTANCE
  Abstract: The microscopic origin of the 18 Angstrom period in the oscillatory interlayer exchange coupling of Fe/Cr(100) and (211) superlattices is investigated by alloying the Cr spacer with V to alter its Fermi surface. The addition of V increases or decreases in size the various Fermi surface calipers that are candidates for governing the oscillation period, such as those that span the ellipse, lens, octahedron, and nested sheets. Epitaxial sputtered superlattices of (100) and (211) orientation were grown and characterized via magnetoresistance measurements as a function of spacer layer thickness for different V-doping levels. A small decrease of the oscillation period is found experimentally which strongly implicates the N-centered ellipse as the origin of the 18 Angstrom period in Fe/Cr superlattices. (C) 1999 American Institute of Physics. [S0021-8979(99)67908-7].
• Record 4 of 10.
  Authors: Santos-VC Fernandes-AAR
  Title: Magnetic Effect in Multilayer Fe/Cr Films
  Full source: JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS 1999, Vol 10, Iss 1, pp 67-70
  Language: English
  Document type: Article
  IDS/Book No.: 190DG
  No. Related Records: 20
  No. cited references: 16
  Addresses: INST-MIL-ENGN, BR-22290270 RIO-DE-JANEIRO, BRAZIL
  KeyWords Plus: INTERLAYER EXCHANGE; FE LAYERS; CR; ANISOTROPIES; RESONANCE
  Abstract: Ferromagnetic resonance measurements on different Fe/Cr multilayer samples with the same thickness of the spacing Cr layers suggest that these multilayers have a different magnetic behavior depending on the thickness of the active Fe layers. In this work we show that the change of magnetic behavior from bulk mode to surface mode is observed only when the thickness of the Fe layers is less than 4 nm. This is attributed to the Fe layer thickness and to the relative thickness of the magnetic and non-magnetic layers. (C) 1999 Kluwer Academic Publishers.
• Record 5 of 10.
  Authors: Okulov-VI Ustinov-VV Pamyatnykh-EA Slovikovskaya-VV
  Title: Acoustic Magnetic-Resonance in Absorption and Dispersion of Surface Elastic-Waves in Multilayers
  Full source: LOW TEMPERATURE PHYSICS 1999, Vol 25, Iss 2, pp 148-150
  Language: English
  Document type: Article
  IDS/Book No.: 171DN
  No. Related Records: 20
  No. cited references: 6
  Addresses: RUSSIAN-ACAD-SCI, INST MET PHYS, URAL BRANCH, EKATERINBURG 620219, RUSSIA
  URAL-STATE-UNIV, EKATERINBURG 620083, RUSSIA
  KeyWords Plus: GIANT MAGNETORESISTANCE
  Abstract: It is shown that magnetic resonances related to excitation of oscillations of the layer magnetization can appear in the spectrum and absorption of the Love acoustic surface waves propagating in a multilayered film with a Fe/Cr type magnetic ordering on a massive substrate. The magnetoelastic resonant contribution to the elastic shear modulus of the film is calculated and the relation between the resonant frequencies and the frequencies of electromagnetically excited uniform ferromagnetic resonance is established. (C) 1999 American Institute of Physics. [S1063-777X(99)01102-0].
  Cited references:
  BEBENIN-NG-1997-J-MAGN-MAGN-MATER-V165-P468
  CAMLEY-RE-1993-J-PHYS-CONDENS-MAT-V5-P3727
  GUREVICH-AG-1994-MAGNETIC-OSCILLATION
  LEVY-M-1983-J-MAGN-MAGN-MATER-V35-P139
  LEVY-PM-1994-SOLID-STATE-PHYS-V47-P367
  MASHAROVA-IS-1996-PISMA-ZH-TEKH-FIZ-V22-P53
  
• Record 6 of 10.
  Authors: Burgler-DE Meisinger-F Schmidt-CM Schaller-DM Guntherodt-HJ Grunberg-P
  Title: Inplane Momentum Conservation in Fe/Cr/Au/Fe(001) Layered Structures
  Full source: PHYSICAL REVIEW B-CONDENSED MATTER 1999, Vol 60, Iss 6, pp R3732-R3734
  Language: English
  Document type: Article
  IDS/Book No.: 226AA
  No. Related Records: 20
  No. cited references: 13
  Addresses: KFA-JULICH-GMBH, FORSCHUNGSZENTRUM, INST FESTKORPERFORSCH, POSTFACH 1913, D-52425 JULICH, GERMANY
  UNIV-BASEL, INST PHYS, CH-4056 BASEL, SWITZERLAND
  KeyWords Plus: FE/CR MULTILAYERS; MAGNETIC MULTILAYERS; EXCHANGE; GROWTH; FILMS; FE
  Abstract: We study the effect of an Au layer at one of the Cr/Fe interfaces in epitaxial Fe/Cr/Au/Fe(001) sandwich structures on the magnetic interlayer coupling behavior by magneto-optical Kerr effect measurements and on the growth by scanning tunneling microscopy. The main effect of the Au layer is the suppression of the long-period oscillations of the magnetic interlayer coupling, while the short-period oscillations become dominant although their amplitude is stronger attenuated than proportional to D-2?, where D is the total thickness of the nonferromagnetic spacer layers. These findings are explained with the shapes of the Fermi surfaces of the spacer materials (Au and Cr) and in-plane momentum conservation at the Cr/Au interface of the electrons that mediate the coupling. This interpretation implicates that the N-centered ellipse of the Cr Fermi surface is the origin of the long-period oscillations across Cr spacers. [S0163-1829(99)51030-8].
• Record 7 of 10.
  Authors: Koelling-DD
  Title: Long-Period Oscillation in the Magnetic Coupling Through Chromium in a Magnetic Multilayer - Bulk Issues
  Full source: PHYSICAL REVIEW B-CONDENSED MATTER 1999, Vol 59, Iss 9, pp 6351-6367
  Language: English
  Document type: Article
  IDS/Book No.: 178EX
  No. Related Records: 20
  No. cited references: 69
  Addresses: ARGONNE-NATL-LAB, DIV MAT SCI, 9700 S CASS AVE, ARGONNE, IL 60439, USA
  KeyWords Plus: POSITRON-ANNIHILATION RADIATION; FE/CR MULTILAYERS; GIANT MAGNETORESISTANCE; ELECTRONIC-STRUCTURE; PARTIAL CONFINEMENT; BAND STRUCTURES; CR INTERLAYERS; EPITAXIAL CR; FE LAYERS; EXCHANGE
  Abstract: The long period oscillation of magnetic coupling through Cr as the spacer layer of especially Fe/Cr magnetic multilayers is examined. It is shown that a reasonable empirical adjustment of the d-band position does bring calipers on the N-centered ellipses into agreement with experiment. The lens surface becomes too small and more anisotropic providing further evidence that it is not involved. However, the neck of the jack surface does reach the proper size and so accounts for the photoemission observations. A mechanism of mode coupling to enhance the strength of the long period oscillation is examined and rejected. A thorough examination of the Cr/(V,Mn) alloy spacer data strongly suggests instead a predilection for mode exclusion. [S0163-1829(99)00309-4].
• Record 8 of 10.
  Authors: Kawakami-RK Rotenberg-E Escorciaaparicio-EJ Choi-HJ Wolfe-JH Smith-NV Qiu-ZQ
  Title: Determination of the Magnetic Coupling in the Co/Cu/Co(100) System with Momentum-Resolved Quantum-Well States
  Full source: PHYSICAL REVIEW LETTERS 1999, Vol 82, Iss 20, pp 4098-4101
  Language: English
  Document type: Article
  IDS/Book No.: 196QW
  No. Related Records: 20
  No. cited references: 23
  Addresses: UNIV-CALIF-BERKELEY, DEPT PHYS, BERKELEY, CA 94720, USA
  UNIV-CALIF-BERKELEY, LAWRENCE BERKELEY LAB, ADV LIGHT SOURCE, BERKELEY, CA 94720, USA
  KeyWords Plus: SHORT-PERIOD OSCILLATIONS; LAYER THICKNESS; CU FILMS; PHOTOEMISSION; MULTILAYERS; MAGNETORESISTANCE; SUPERLATTICES; CO(100); CU(100); FE/CR
  Abstract: The relation between the quantum well (QW) states and the oscillatory magnetic coupling in Co/Cu/Co grown on Cu(100) was investigated by angle resolved photoemission spectroscopy, magnetic x-ray linear dichroism, and the surface magneto-optic Kerr effect. The QW states were explained quantitatively using the phase accumulation model, and the derived QW phases at the Cu/Co interface were used to calculate the interlayer coupling. The agreement between this calculation and the experimental result reveals that the phase relation between the long- and short-period couplings is determined by the phase relation of the QW states in k space.
• Record 9 of 10. State: interesting on a first glance. Must be read again! (Some possible data/conclusions?)
  Authors: Akinshina-LP Kobelev-AV Koshta-AA Milyaev-MA Minin-VI Romanyukha-AA
  Title: FMR Line Splitting in Fe/Cr Multilayers
  Full source: PHYSICA STATUS SOLIDI B-BASIC RESEARCH 1999, Vol 214, Iss 1, pp 153-164
  Language: English
  Document type: Article
  IDS/Book No.: 235NF
  No. Related Records: 20
  No. cited references: 18
  Addresses: RUSSIAN-ACAD-SCI, INST MET PHYS, URALS DIV, EKATERINBURG 620219, RUSSIA
  KeyWords Plus: FE FILMS; EXCHANGE; SUPERLATTICES
  Abstract: Measurements of the magnetization curves and ferromagnetic resonance (FMR) were made on a series of samples of multilayers [Fe(13 Angstrom)/Cr(t(Cr))](12), with 7 Angstrom < t(Cr) < 40 Angstrom, deposited by the method of molecular-beam epitaxy on a sapphire substrate with the Fe buffer layer of 40 Angstrom thickness. The effective demagnetizing field 4 pi M-s, - H'(u) was estimated for all samples from the angular dependence of an FMR resonant field and linewidth for the uniform mode at the transverse excitation, where M-s is the saturation magnetization of the Fe layer, H'(u) is the uniaxial anisotropy field. An additional FMR line was observed for samples with small spacer thickness (t(Cr) < 16 Angstrom). Its intensity was equal to that of a main line under the condition of t(Cr) approximate to t(Fe) approximate to 12 Angstrom, decreasing down to zero both at reduction, and at the increase of t(Cr). The FMR lineshape in a field parallel to the surface was simulated by a superposition of two curves, possessing in view of the magnetization curve approximately Lorentzian shape with different effective field values H'(u). The possible reason of the features observed can be the formation of regions with different effective anisotropy field values in a sample plane during the deposition. For all samples investigated at longitudinal excitation, an FMR signal which corresponds to an optical mode was not observed.
• Record 10 of 10.
  Authors: Stiles-MD
  Title: Interlayer Exchange Coupling
  Full source: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 1999, Vol 200, Iss 1-3, pp 322-337
  Language: English
  Document type: Review
  IDS/Book No.: 241DP
  No. Related Records: 20
  No. cited references: 133
  Addresses: NATL-INST-STAND-&-TECHNOL, ELECTRON PHYS GRP, BLDG 220 RM B206, GAITHERSBURG, MD 20899, USA
  Author keywords: Interlayer Exchange Coupling; Spacer-Layer Thickness; Fermi Surfaces; RKKY Interaction
  KeyWords Plus: QUANTUM-WELL STATES; LAYERED MAGNETIC-STRUCTURES; MOLECULAR-BEAM EPITAXY; AB-INITIO CALCULATIONS; GIANT MAGNETORESISTANCE; FERROMAGNETIC-LAYERS; FE/CR MULTILAYERS; TEMPERATURE-DEPENDENCE; OSCILLATION PERIODS; CO/RU MULTILAYERS
  Abstract: The extensive research done on interlayer exchange coupling in transition metal multilayers has resulted in a deep understanding of this coupling and a remarkable agreement between theoretical results and measurements. The coupling between two magnetic layers separated by a non-magnetic spacer layer is mediated by the electrons of the spacer layer. The coupling, which oscillates in sign as a function of the thickness of the spacer layer, is closely related to the well-known RKKY interaction between magnetic impurities. Due to the existence of many high-quality measurements, it has been much more fully developed theoretically than the interaction between impurities. Theory predicts that the periods of the oscillatory coupling should depend on critical spanning vectors of the Fermi surface belonging to the spacer-layer material There is remarkable agreement far the measured periods and those predicted from the Fermi surfaces. There is also substantial agreement between theory and experiment on the strength of the coupling. This review presents the comparison between theory and experiment in some detail. (C) 1999 Published by Elsevier Science B.V. All rights reserved.
• Title: Hyperfine Fields in Fe-Cr Thin-Films
  Authors: Karas-W
  Full source: VACUUM 1999, Vol 54, Iss 1-4, pp 295-297
  Abstract: We have calculated the electronic structure of the 2Cr/3Fe/2Cr slab in bcc(1 1 0) geometry using FLAPW method in the local spin density approximation (LDA). The main aim of this work was to compare the calculated values of the hyperfine fields (H-f) with these obtained in the experiment carried out by Zukrowski et al. (J. Magn. Magn. Mater, 1995, 145, 97). Our calculation shows the influence of the ordering on the Fe hyperfine fields and for the measured Cr/3.3Fe/Cr film we suggest the existence of two different H-f values in each Fe plane, differing by 0.4-0.8 T. The magnetic moments of chromium are near 0.7 mu(B) on the surface and oppositely oriented in the plane, while subsurface moments are small and anti-parallel to iron spins. The moments of iron atoms on the interface are slightly reduced. (C) 1999 Elsevier Science Ltd. All rights reserved.
• Title: Homoepitaxial growth of iron and a real space view of reflection-high-energy-electron diffraction(Also in ps
  Authors: Joseph A. Stroscio, D. T. Pierce, and R. A. Dragoset
  Source: Physical Review Letters 70, 3615-3618 (1993)

  Abstract: We report real space views of the homoepitaxial growth of Fe on Fe(001) whiskers observed by scanning tunneling microscopy. A measure of the surface diffusion of the Fe atoms is obtained over the temperature range of 20-250 °C. The effect of the diffusion kinetics is observed in the surface morphology as a decrease in the interface width with temperature. Measurements of reflection-high-energy-electron diffraction during growth allow a comparison of real and reciprocal space techniques.

• Title: Influence of Cr growth on exchange coupling in Fe/Cr/Fe(100)(Also in ps)
  Authors: D. T. Pierce, Joseph A. Stroscio, J. Unguris, and R. J. Celotta
  Source: Physical Review B 49, 14564-14572 (1994)

  Abstract: Scanning electron microscopy with polarization-analysis (SEMPA) measurements of the dependence of the oscillations of the exchange coupling in Fe/Cr/Fe(100) structures on the Cr growth temperature are correlated with the thickness fluctuations in Cr films measured by scanning tunneling microscopy (STM) at similar growth temperatures. Layer-by-layer growth was observed by STM for Cr deposition on very flat Fe(100) whiskers at deposition temperatures <= 300 °C. The SEMPA measurements of the magnetization of the Fe overlayer as a function of Cr spacer-layer thickness at this temperature could be simulated well by oscillatory coupling with periods 2.105±0.005d and 12±1d, where d is the layer spacing. Rougher Cr growth, limited by diffusion kinetics, occurs at lower growth temperatures giving a distribution of thicknesses in the growth front as determined by STM. We modeled the Fe magnetization for lower-temperature Cr growth by assuming that the exchange coupling at each discrete Cr thickness is the same as found for layer-by-layer growth. The total coupling at each average Cr spacer-layer thickness was determined by adding the weighted contribution to the coupling from each Cr layer thickness contributing to the average thickness. Thus, by taking into account the thickness fluctuations in the Cr spacer layer as determined by STM, very good agreement was obtained between the model and the SEMPA measurement of the Fe overlayer magnetization for Cr growth at lower temperatures without including other consequences of roughness at the interface, such as the breakdown of translational invariance. Important characteristic length scales and the role of biquadratic coupling in the SEMPA measurements are addressed.

• Title: Atomic-scale observations of alloying at the Cr-Fe(001) interface
  Authors: A. Davies, Jospeh A. Stroscio, D. T. Pierce, and R. J. Celotta
  Source: Physical Review Letters -- May 27, 1996 -- Volume 76, Issue 22, pp. 4175-4178

  Abstract: While much progress has been made using epitaxial growth of Fe/Cr/Fe structures to study magnetic exchange coupling, a number of anomalies have arisen in studies of this model system. Using scanning tunneling microscopy and spectroscopy to investigate Cr growth on Fe(001), we have identified a potential structural cause of these anomalies. We show that Cr growth under layer-by-layer conditions on Fe(001) leads to the formation of a Cr-Fe alloy. We exploit a Cr and Fe surface state to identify single Cr impurities in Fe and evaluate the alloy concentrations with increasing Cr coverage.

• Title: Interface alloying at Fe/Cr interfaces and its role in exchange coupling, angular resolved Auger electron, magneto-optic Kerr effect, and Brillouin light scattering studies (invited)
  Authors: B. Heinrich, J. F. Cochran, D. Venus, K. Totland, D. Atlan, S. Govorkov, and K. Myrtle
  Source: Journal of Applied Physics -- April 15, 1996 -- Volume 79, Issue 8, pp. 4518-4523

  Abstract: Angular resolved Auger electron studies were carried out for Fe whisker/Cr(001) interfaces which were prepared at 100, 180, 246, and 296 °C. The Cr atoms penetrate progressively into the second (counting from the surface) atomic layer at 100, 180, and 246 °C. At 296 °C the Cr atoms enter the third atomic layer. No noticeable fraction of the Cr atoms was found in the fourth atomic layer. The exchange coupling was studied in Fe whisker/Cr/Fe(001) films which were grown in a nearly perfect layer by layer mode. Magneto-optic Kerr effect and Brillouin light scattering measurements showed that the measured change in the phase of the short wavelength oscillations, the presence of a slowly varying exchange coupling bias, and the small measured values of exchange coupling are caused by the same mechanism: interface alloying. The exchange coupling in Fe whisker/Cr/nFe specimens, for n=10, 20, 30, and 40 ML, showed no obvious dependence on the Fe layer thickness. ©1996 American Institute of Physics.

• Title: Interfacial mixing of ultrathin Cr films grown on an Fe whisker
  Authors: D. Venus and B. Heinrich
  Source: Physical Review B 53, R1733-R1736 (1996)

  Abstract: 1/2-ML Cr films grown on an Fe whisker have been studied using angle-resolved Auger electron forward scattering as a function of the substrate temperature at which the Cr was deposited. The angular scans of the peak-to-peak Cr Auger intensity show pronounced peaks due to forward scattering, which indicate significant intermixing of Cr atoms into the second layer for films grown at 100, 180, and 246 °C, and into the third layer for the film grown at 296 °C. Calculations based on a single-scattering theory show that half of the Cr deposited at 296 °C is below the surface. Since previous studies of exchange coupling through Cr films used samples grown at this elevated temperature, the alloying may be related to the earlier finding that the exchange coupling through Cr(001) is much weaker than, and of opposite phase to, that predicted by first-principles calculations.

• Title: Enhanced magnetoresistance in annealed and Cr doped Fe/Cr multilayers
  Authors: N. M. Rensing, B. M. Clemens, D. L. Williamson
  Source: Journal of Applied Physics -- May 15, 1996 -- Volume 79, Issue 10, pp. 7757-7762

  Abstract: In previous work we reported that the magnetoresistance of Fe/Cr multilayers can be increased by annealing the films at moderate temperatures, which increases the spin-dependent scattering of the conduction electrons. Here we present Mössbauer data that demonstrate that the structural effect of annealing is to promote Cr interdiffusion into the bulk of the iron layers rather than short scale intermixing at the interfaces. We have also investigated the effect of increasing the asymmetric scattering by adding chromium to the iron in Fe/Cr multilayers. The additional Cr was either alloyed with the Fe in compositions ranging from 1.5% to 50% Cr in Fe, or concentrated into 1 or 2 Å layers embedded at various positions in the Fe. We report enhanced room-temperature magnetoresistance of up to 11.4% in sputter-deposited Fe/Cr multilayers when the Fe layers are doped with 20% Cr. The maximum magnetoresistance observed for samples with embedded Cr layers was 10.5%. In comparison, the magnetoresistance was 7.5% in a similar, undoped sample. ©1996 American Institute of Physics.

• Temperature dependence of the hyperfine field and magnetization in ultrathin epitaxial Fe films(also in ps)
  G. Lugert and G. Bayreuther
  Physical Review B 38, 11068-11074 (1988)

  Abstract:Conversion-electron Mössbauer spectroscopy and superconducting quantum interference device magnetometry have been used to measure the magnetic hyperfine field and the spontaneous magnetization of ultrathin Fe(110) films grown epitaxially on Ag(111) substrate films as a function of temperature. For the first time, hyperfine-field data with monolayer resolution and magnetization data are obtained from the same sample consisting of four Fe(110) atomic layers. A comparison of the present results to previous experiments and theories leads to the following conclusions: (1) the ground-state hyperfine field at the Fe(110)/Ag(111) interface is enhanced relative to bulk in agreement with other experiments, but in disagreement with recent band calculations; this discrepancy may be explained by considering dipolar field contributions at the interface; (2) the relative spin deviation from saturation (T=0) measured by the hyperfine field is the same as measured by the spontaneous magnetization for the interface atoms as well as for the center of the film; (3) the spin deviation, Delta M(T), is well described by a T3/2 law in all layers of an ultrathin Fe film; hence, a linear M-T relation is not a characteristic feature of a two-dimensional ferromagnet, as often quoted in the literature; (4) ultrathin Fe films show pronounced surface and size effects of the thermally excited spin deviation; no theory exists at present which includes layer-dependent ground-state moments, surface and bulk spin waves; and (5) the spin-wave parameter, B, differs in different experiments for similar film systems. It is suggested that the structure and roughness of the interface in real films play an important role.