Those articles are related to the published one (J. Dekoster et al.)
Authors: means related article(s).
SCI CDE with Abstracts (Jan 99 - Dec 99) (D4.1)
Record 1 of 20. Title: Interlayer Exchange Coupling Between 2 Ferromagnets with Finite Thickness Separated by a Nonmetallic Spacer Authors: Wang-JZ Li-BZ Full source: PHYSICAL REVIEW B-CONDENSED MATTER 1999, Vol 59, Iss 9, pp 6383-6389Abstract: Interlayer exchange coupling (IEC) between two ferromagnets (FM's) separated by a nonmetallic spacer is analyzed theoretically within the free-electron approximation. Particular attention is paid to the influence of FM thickness d(FM) On IEC and the variation of Fermi energy with the alignment of two FM's. The results show that (I)d(FM) strongly influence the IEC such that, only when d(FM) is not large, the barrier height and molecular field are both small, the IEC may oscillate with the spacer thickness owing to the quantum-size effect; otherwise, the IEC does not oscillate, but exhibits an exponential behavior in most spacer thickness; (2) as an oscillatory function of d(FM) with multiple periods, the IEC has a negative nonoscillatory term, which will become zero when the molecular field is comparatively small; (3) the Fermi energy has little difference between the parallel and antiparallel alignments of the two FM's, which correlates with the IEC to some extent. Particularly, with the increasing of d(FM) this correlation becomes stronger. [S0163-1829(99)01409-5].
Authors: BRUNO-P-1995-PHYS-REV-B-V52-P411 DEVRIES-JJ-1997-PHYS-REV-LETT-V78-P3023 FULLERTON-EE-1992-J-MAGN-MAGN-MATER-V117-PL301 MATTSON-JE-1993-PHYS-REV-LETT-V71-P185 SLONCZEWSKI-JC-1989-PHYS-REV-B-V39-P6995 TOSCANO-S-1992-J-MAGN-MAGN-MATER-V114-PL6
Record 2 of 20. Title: Magnetic-Properties and Magnetoresistance of Granular Evaporated Fe/Si Films Authors: Ihara-N Narushima-S Kijima-T Abeta-H Saito-T Shinagawa-K Tsushima-T Full source: JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS 1999, Vol 38, Iss 11, pp 6272-6281Abstract: Fe (3.4 Angstrom) and Si (6 Angstrom) are evaporated alternately onto silica substrates to realize a granular structure. The substrate temperature T-s during the evaporation is changed from 100 K to 623 K to vary the film structures. The specimens of T-s greater than or equal to room temperature (RT) are superparamagnetic at RT, which suggests a granular structure. Magnetoresistance (MR) at RT is negative (resistivity decreases with increasing magnetic field H) for all specimens. It is thought that the negative MR is attributable to the granular structure. On the other hand, at 77 K a positive MR linear with H (not H-2) up to 50 kOe is observed for all specimens. The linear dependence on H of the positive MR may be due to the nonuniformity in the granular structure. The positive MR itself and the change of the sign of MR from negative to positive with decreasing temperature have not been observed in conventional granular systems such as Co-Ag and Co-Al-O.
Authors: BRUNO-P-1995-PHYS-REV-B-V52-P411 CHAIKEN-A-1996-PHYS-REV-B-V53-P5518 DEVRIES-JJ-1997-PHYS-REV-LETT-V78-P3023 FULLERTON-EE-1992-J-MAGN-MAGN-MATER-V117-PL301 MATTSON-JE-1993-PHYS-REV-LETT-V71-P185 TOSCANO-S-1992-J-MAGN-MAGN-MATER-V114-PL6
Record 3 of 20. Title: Formation of Nonmagnetic C-Fe1-Xsi in Antiferromagnetically Coupled Epitaxial Fe/Si/Fe Authors: Strijkers-GJ Kohlhepp-JT Swagten-HJM Dejonge-WJM Full source: PHYSICAL REVIEW B-CONDENSED MATTER 1999, Vol 60, Iss 13, pp 9583-9587Abstract: Low-energy electron diffraction, Auger electron spectroscopy, and conversion electron Mossbauer spectroscopy have been applied to study antiferromagnetically exchange-coupled epitaxial Fe/Si/Fe(100). It is shown that a bcc-like (100) structure is maintained throughout the layers after a recrystallization of the spacer layer by Fe/Si interdiffusion. Direct experimental evidence is presented that c-Fe1-xSi (0 less than or equal to x less than or equal to 0.5) is formed in the spacer layer, a nonmagnetic metallic metastable iron silicide phase with a CsCl structure (B2), which supports explanations for the antiferromagnetic exchange coupling given recently.
Authors: BRUNO-P-1995-PHYS-REV-B-V52-P411 CHAIKEN-A-1996-PHYS-REV-B-V53-P5518 DEKOSTER-J-1995-MATER-RES-SOC-SYMP-P-V382-P253 DEVRIES-JJ-1997-PHYS-REV-LETT-V78-P3023 FULLERTON-EE-1992-J-MAGN-MAGN-MATER-V117-PL301
Record 4 of 20. Title: Microscopic Environment of Fe in Epitaxially Stabilized C-Fesi Authors: Fanciulli-M Weyer-G Svane-A Christensen-NE Vonkanel-H Muller-E Onda-N Miglio-L Tavazza-F Celino-M Full source: PHYSICAL REVIEW B-CONDENSED MATTER 1999, Vol 59, Iss 5, pp 3675-3687Abstract: Epitaxially stabilized iron monosilicide films having the CsCl structure (c-FeSi) have been investigated by conversion electron Mossbauer spectroscopy and transmission electron microscopy. The Fe-57 Mossbauer parameters (isomer shift delta, linewidth Gamma, and quadrupole splitting Delta) are reported and discussed in terms of the local surrounding of the Fe nucleus. High statistical accuracy and resolution allowed a detailed investigation of the effects of strain and of the structural phase transformation from the epitaxially stabilized to the bulk stable phase, The phase transformation was found to proceed in a rather surprising layer by layer mechanism with smooth interfaces between the epitaxially stabilized, the bulk stable, and a third phase. Results from a molecular-dynamics simulation at constant pressure and temperature of the structural phase transition are presented and compared with the experimental findings. The isomer shift and the electric-field gradient at the Fe nucleus in the strained c-FeSi and in the third phase have been calculated using the ab initio full potential linear muffin-tin orbital method. The Mossbauer parameters of some relevant point defects in c-FeSi have likewise been calculated within this framework. [S0163-1829(99)01302-8].
Authors: CHAIKEN-A-1996-PHYS-REV-B-V53-P5518 DEKOSTER-J-1995-MATER-RES-SOC-SYMP-P-V382-P253 DEVRIES-JJ-1997-PHYS-REV-LETT-V78-P3023 MADER-KA-1993-PHYS-REV-B-V48-P4364 VONKANEL-H-1994-PHYS-REV-B-V50-P3570
Record 5 of 20. Title: Cohesive, Structural, and Electronic-Properties of Fe-Si Compounds Authors: Moroni-EG Wolf-W Hafner-J Podloucky-R Full source: PHYSICAL REVIEW B-CONDENSED MATTER 1999, Vol 59, Iss 20, pp 12860-12871Abstract: Phase stability, structural, and electronic properties of iron silicides in the Fe3Si, FeSi, and FeSi2 compositions are investigated by first-principle density-functional calculations based on ultrasoft pseudopotentials and all-electron methods. Structural stabilization versus spin-polarization effects are discussed at the Fe3Si composition, while for epsilon-FeSi and beta-FeSi2 we investigate their structural properties and the corresponding semiconducting band properties. All the computed results are analyzed and compared to available experimental data. The stability of the bulk phases, the lattice parameters, the cohesive energies and magnetic properties are found to be in good agreement with experiment when using the generalized gradient approximations for the exchange-correlation functional. Density-functional calculations are unable to account for the small bulk modulus of epsilon-FeSi despite that the computed lattice constant and internal atomic positions coincide with the experimental results. Both full-potential and ultrasoft-pseudopotential methods confirm for beta-FeSi2 the indirect nature of the fundamental gap, which is attributed to a transition between Y to 0.6X Lambda being 30% smaller than the experimental gap. Ultrasoft pseudopotential calculations of Fe-Si magnetic phases and of various nonequilibrium metallic phases at the FeSi and FeSi2 composition are presented. These calculations provide nb initio information concerning the stabilization of metallic pseudomorphic phases via high pressures or epitaxy. [S0163-1829(99)05419-3].
Authors: BOST-MC-1985-J-APPL-PHYS-V58-P2696 MADER-KA-1993-PHYS-REV-B-V48-P4364 MATTSON-JE-1993-PHYS-REV-LETT-V71-P185 TOSCANO-S-1992-J-MAGN-MAGN-MATER-V114-PL6 VONKANEL-H-1994-PHYS-REV-B-V50-P3570
Record 6 of 20. Title: Heat-Induced Antiferromagnetic Coupling in Multilayers with ZnSe Spacers Authors: Walser-P Hunziker-M Speck-T Landolt-M Full source: PHYSICAL REVIEW B-CONDENSED MATTER 1999, Vol 60, Iss 6, pp 4082-4086Abstract: Two ferromagnetic films separated by an amorphous semiconducting spacer are exchange coupled across the spacer layer. The coupling is reversibly temperature dependent with a positive temperature coefficient. As spacer material we use amorphous ZnSe which is a compound semiconductor and find heat-induced antiferromagnetic coupling in striking similarity to amorphous Si and Ge. In an Fe/alpha-ZnSe/Fe trilayer with spacer thickness between 18 Angstrom and 22 Angstrom the coupling is antiferromagnetic with a positive temperature coefficient. At slightly larger thicknesses between 22 Angstrom and 25 Angstrom we find a reversible transition from ferromagnetic coupling at low temperatures to antiferromagnetic coupling at higher temperatures upon heating. We discuss the reversibly heat-induced effective exchange coupling in terms of localized defect states in the band gap in the vicinity of the Fermi energy. [S0163-1829(99)04230-7].
Authors: CHAIKEN-A-1996-PHYS-REV-B-V53-P5518 DEVRIES-JJ-1997-PHYS-REV-LETT-V78-P3023 FULLERTON-EE-1992-J-MAGN-MAGN-MATER-V117-PL301 GRUNBERG-P-1986-PHYS-REV-LETT-V57-P2442 TOSCANO-S-1992-J-MAGN-MAGN-MATER-V114-PL6
Record 7 of 20. Title: Heat-Induced Coupling in Multilayers with Semiconducting Spacers Authors: Walser-P Landolt-M Full source: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 1999, Vol 199, Iss JUN, pp 412-414Abstract: Two ferromagnetic films separated by an amorphous semiconducting spacer are exchange coupled across the spacer layer. The coupling is reversibly temperature dependent with a positive temperature coefficient. (C) 1999 Elsevier Science B.V. All rights reserved.
Authors: BRINER-B-1994-PHYS-REV-LETT-V73-P340 CHAIKEN-A-1996-PHYS-REV-B-V53-P5518 DENBROEDER-FJA-1995-PHYS-REV-LETT-V75-P3026 DEVRIES-JJ-1997-PHYS-REV-LETT-V78-P3023
Record 8 of 20. Title: Interlayer Coupling of Fe/Si/Fe Trilayers with Very Thin Boundary-Layers Authors: Endo-Y Kitakami-O Shimada-Y Full source: JOURNAL OF APPLIED PHYSICS 1999, Vol 85, Iss 8, pp 5741-5743Abstract: The interlayer magnetic coupling of a Fe/Si/Fe trilayer shows an analogous feature to that of Fe/Si superlattices. With an increase in Si layer thickness, it oscillates as ferromagnetic (first F), antiferromagnetic (AF), ferromagnetic (second F), and finally reaches a noncoupling (N) state. We have investigated interlayer coupling of Fe/Si/Fe trilayers inserting very thin (1 or 2 ML thick) boundary layers X (X=Ag, Ge, Fe-Si, Ta, etc.). They are expected to suppress interatomic diffusion between Fe and Si layers. Interlayer coupling of Fe/X/Si/X/Fe with negligible interdiffusion is simply F and changes to N as the Si layer thickness increases. Furthermore, Fe/Fe-Si/Fe trilayers which show coupling of first F, AF but not second F, reproduce second F when a Si layer is inserted in the Fe-Si spacer. These results imply that an amorphous Si spacer mediates ferromagnetic coupling between neighboring Fe layers while the first F and the strong AF coupling usually observed in Fe/Si superlattices are caused by diffused crystalline Fe-Si. (C) 1999 American Institute of Physics. [S0021-8979(99)45508-2].
Authors: CHAIKEN-A-1996-PHYS-REV-B-V53-P5518 DEVRIES-JJ-1997-PHYS-REV-LETT-V78-P3023 FULLERTON-EE-1992-J-MAGN-MAGN-MATER-V117-PL301 TOSCANO-S-1992-J-MAGN-MAGN-MATER-V114-PL6
Record 9 of 20. Title: Amorphous Fe-Si and Fe-Ge Nanostructures Quantitatively Analyzed by X-Ray-Photoelectron Spectroscopy Authors: Schleberger-M Walser-P Hunziker-M Landolt-M Full source: PHYSICAL REVIEW B-CONDENSED MATTER 1999, Vol 60, Iss 20, pp 14360-14365Abstract: The subject of this paper is an x-ray-photoelectron spectroscopy investigation of amorphous Fe-Si and Fe-Ge nanostructures that have attracted interest because of their magnetic coupling properties. To this end we deposit Fe onto clean, amorphous Si and Ge substrates at room temperature and at 40 K, respectively. We take spectra of the Fe3p, Fe2p, and Si2p core Levels to determine possible chemical shifts. The results indicate a charge transfer from the Fe to the Si and Ge atoms at room temperature as well as at 40 K. Additionally, we record wide range spectra of the SiKLL, GeLMM, and the Fe2p peaks as well as spectra of Fe-Si, and Fe-Ge compounds, respectively. Analyzing the inelastic background of the peaks we quantitatively determine the nanostructure of the deposits. We can exclude the formation of sharp interfaces. Instead, we find evidence for the formation of an Fe-Si or Fe-Ge interface compound with a homogeneous composition. For magnetically investigated low-temperature prepared Fe/Si/Fe trilayers we show that the spacer layer is a pure semiconductor with a thickness that is reduced compared to the nominal value. [S0163-1829(99)02443-1].
Authors: CHAIKEN-A-1996-PHYS-REV-B-V53-P5518 DEVRIES-JJ-1997-PHYS-REV-LETT-V78-P3023 FULLERTON-EE-1992-J-MAGN-MAGN-MATER-V117-PL301 TOSCANO-S-1992-J-MAGN-MAGN-MATER-V114-PL6
Record 10 of 20. Title: Antiferromagnetic Coupling in Co/Ge Superlattices Authors: Endo-Y Kikuchi-N Kitakami-O Shimada-Y Full source: JOURNAL OF PHYSICS-CONDENSED MATTER 1999, Vol 11, Iss 15, pp L133-L137Abstract: We have investigated interlayer coupling of Co/Ge superlattices. The present experiments obviously show that the coupling changes from ferromagnetic (F) to antiferromagnetic (AF) and finally to non-coupling (N) with the increase of Ge layer thickness. This coupling behaviour, as a function of the spacer thickness, is very similar to that of Fe/Si superlattices, although the coupling strength is much smaller than the latter: namely, similar to 0.05 erg cm(-2) for Co/Ge and similar to 1.0 erg cm(-2) for Fe/Si. Precise structural characterization indicates that diffused spacers at Co/Ge interfaces are responsible for the AF coupling. The same coupling behaviour has also been observed in Co/non-magnetic Co-Ge superlattices, where interdiffusion at the interfaces is entirely suppressed. All these results clearly demonstrate that the interlayer coupling between neighbouring Co layers is mediated by non-magnetic Co-Ge spacers.
Authors: CHAIKEN-A-1996-PHYS-REV-B-V53-P5518 DEVRIES-JJ-1997-PHYS-REV-LETT-V78-P3023 FULLERTON-EE-1992-J-MAGN-MAGN-MATER-V117-PL301 TOSCANO-S-1992-J-MAGN-MAGN-MATER-V114-PL6
Record 11 of 20. Title: Interlayer Coupling in Fe/Fe1-Xsix Superlattices Authors: Endo-Y Kitakami-O Shimada-Y Full source: PHYSICAL REVIEW B-CONDENSED MATTER 1999, Vol 59, Iss 6, pp 4279-4286Abstract: Interlayer coupling has been investigated for a series of Fe/Fe1-xSix (0.4 less than or equal to x less than or equal to 1.0) superlattices. The layer of Fe1-xSix in the lattices is ferromagnetic for x<0.5 and causes ferromagnetic coupling between Fe layers for all spacer thicknesses investigated here. As the Si content increases above x=0.5, the layer becomes nonmagnetic and simultaneously our current in the plane of the sample and current perpendicular to the sample plane measurements suggest that the spacer rapidly changes its conduction property from metallic to highly resistive. Variations of the interlayer magnetic coupling as a function of spacer layer thickness for the spacer compositions above x=0.5 are similar to each other; namely, with an increase of the spacer thickness the interlayer coupling is initially ferromagnetic, then antiferromagnetic, and finally becomes noncoupling. Moreover, the temperature dependence of the bilinear and biquadratic coupling constants, J(1)(T) and J(2)(T) which were obtained by numerical fitting, varies sensitively with x. Assuming that the conduction of the spacers ranges from metallic to insulating as x increases, all these coupling behaviors can be described qualitatively by the quantum interference model formalized by Bruno. Furthermore, we found that the coupling strength is enhanced dramatically with increase of x of Fe1-xSix. [S0163-1829(99)11405-X].
Authors: CHAIKEN-A-1996-PHYS-REV-B-V53-P5518 DEVRIES-JJ-1997-PHYS-REV-LETT-V78-P3023 FULLERTON-EE-1992-J-MAGN-MAGN-MATER-V117-PL301 TOSCANO-S-1992-J-MAGN-MAGN-MATER-V114-PL6
Record 12 of 20. Title: Heat-Induced Effective Exchange Coupling in Magnetic Multilayers with Semiconductors Authors: Walser-P Hunziker-M Landolt-M Full source: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 1999, Vol 200, Iss 1-3, pp 95-109Abstract: Two ferromagnetic films separated by an amorphous semiconducting spacer layer are exchange coupled across the spacer. The coupling is reversibly temperature dependent with a positive temperature coefficient making such layered systems a 2-D realization of the concept of heat-induced magnetism. By studying ferromagentic Fe layers separated by amorphous Si, Ge, or ZnSe layers we explore the possibilities to generate such an effective exchange coupling and address the question of the mechanism responsible for it. (C) 1999 Elsevier Science B.V. All rights reserved.
Authors: BRINER-B-1994-PHYS-REV-LETT-V73-P340 CHAIKEN-A-1996-PHYS-REV-B-V53-P5518 DENBROEDER-FJA-1995-PHYS-REV-LETT-V75-P3026 DEVRIES-JJ-1997-PHYS-REV-LETT-V78-P3023
Record 13 of 20. Title: Pure Nuclear Bragg Reflection of a Periodic Fe-56/Fe-57 Multilayer Authors: Deak-L Bayreuther-G Bottyan-L Gerdau-E Korecki-J Kornilov-EI Lauter-HJ Leupold-O Nagy-DL Petrenko-AV Pasyuklauter-VV Reuther-H Richter-E Rohloberger-R Szilagyi-E Full source: JOURNAL OF APPLIED PHYSICS 1999, Vol 85, Iss 1, pp 1-7Abstract: Grazing incidence nuclear multilayer diffraction of synchrotron radiation from a periodic stack of alternating Fe-56 and Fe-57 layers was observed. Resonant layer fraction, substrate size, flatness, and surface roughness limits were optimized by previous simulations. The isotopic multilayer (ML) sample of float glass/Fe-57(2.25 nm)/[Fe-56(2.25 nm)/Fe-57(2.25 nm)]X15/Al(9.0 nm) nominal composition was prepared by molecular beam epitaxy at room temperature. Purity structure and lateral homogenity of the isotopic ML film was characterized by magnetometry, Auger electron, Rutherford backscattering, and conversion electron Mossbauer spectroscopies. The isotopic ML structure was investigated by neutron and synchrotron Mossbauer reflectometry. Surface roughness of about 1 nm of the flat substrate (curvature radius > 57 m) was measured by scanning tunneling microscopy and profilometry. A pure nuclear Bragg peak appeared in synchrotron Mossbauer reflectometry at the angle expected from neutron reflectometry while no electronic Bragg peak was found at the same position by x-ray reflectometry. The measured width of the Bragg peak is in accordance with theoretical expectations. (C) 1999 American Institute of Physics. [S0021-8979(99)09201-4].
Authors: CHUMAKOV-AI-1993-PHYS-REV-LETT-V71-P2489 DEAK-L-1996-PHYS-REV-B-V53-P6158 TOELLNER-TS-1995-PHYS-REV-LETT-V74-P3475
Record 14 of 20. Title: Transport-Properties of Sputtered Fe Si Multilayers Authors: Tong-LN Pan-MH Wu-XS Lu-M Zhai-HR Full source: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 1999, Vol 199, Iss JUN, pp 101-103Abstract: A relatively large GMR effect associated with antiferromagnetic (AFM) coupling in sputtered Fe/Si multilayers was observed and the dependence of transport properties on Si layer and Fe layer thickness and on the number of bilayers at room temperature and 77 K were studied. Our data suggests that the mechanism of AFM coupling and GMR effect in Fe/Si multilayers is the same as that in metal/metal systems. (C) 1999 Elsevier Science B.V. All rights reserved.
Authors: CHAIKEN-A-1996-PHYS-REV-B-V53-P5518 MATTSON-JE-1993-PHYS-REV-LETT-V71-P185
Record 15 of 20. Title: Low-Temperature Enhancement of the Magnetic-Anisotropy in Fe Si Multilayers Authors: Zuberek-R Fronc-K Szymczak-R Baran-M Mosiniewiczszablewska-E Gnatchenkob-SL Chizhik-AB Stobiecki-F Szymczak-H Full source: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 1999, Vol 197, Iss MAY, pp 83-84Abstract: The FMR and SQUID investigation of the magnetic anisotropy of Fe/Si multilayers are presented. The multilayers, with various thicknesses of iron and a thick layer of silicon (in order to eliminate the coupling between Fe layers), have been grown by DC sputtering on single crystal GaAs substrates. Low temperature enhancement of the easy-plane anisotropy, especially below 50 K, was observed. This anisotropy seems to be of magnetoelastic origin. The coercivity was shown to decrease with temperature. (C) 1999 Elsevier Science B.V. All rights reserved.
Authors: CHAIKEN-A-1996-PHYS-REV-B-V53-P5518 DEVRIES-JJ-1997-PHYS-REV-LETT-V78-P3023
Record 16 of 20. Title: Magnetic and Electric Properties of Sn-Oxide/M (M=fe, Ni, Co) Multilayers Authors: Matsuyama-K Nishihata-K Komatsu-S Nozaki-Y Full source: IEEE TRANSACTIONS ON MAGNETICS 1999, Vol 35, Iss 5, pp 2901-2903Abstract: Magnetic and electronic properties of novel semiconductive-oxide/ferromagnet multilayers of Sn-oxide and ferromagnetic metals (Fe, Ni, Co), deposited with a multi-target rf magnetron sputtering system, were studied. Among the studied material systems, Co/Sn-oxide sustains well-defined layer structure and ferromagnetic property for the thinnest thickness of 1 nm, A thermionic CPP transport was observed in [Co(2 nm) /Sn-oxide (4 nm)](10), which activation energy was evaluated as 4.4x10(-3) erg from the thermal dependence of conductivity. Negative magnetoresistance was observed in two orthogonal directions of in-plane external fields, which confirms spin dependent transport in Sn-oxide thin film, The measured MR change is 0.6 % (Delta R = 0.8 Omega, R-s=140 Omega) at room temperature.
Authors: FULLERTON-EE-1992-J-MAGN-MAGN-MATER-V117-PL301 TOSCANO-S-1992-J-MAGN-MAGN-MATER-V114-PL6
Record 17 of 20. Title: Optical Phonons in Isotope Superlattices of GaAs, Gap, and GaSb Studied by Raman-Scattering Authors: Gobel-A Ruf-T Fischer-A Eberl-K Cardona-M Silveira-JP Briones-F Full source: PHYSICAL REVIEW B-CONDENSED MATTER 1999, Vol 59, Iss 19, pp 12612-12621Abstract: We have investigated the LO-phonon Raman spectra of [100] oriented gallium isotope superlattices ((GaX)-Ga-69)(n)((GaX)-Ga-71)(n) [X=P,As; both elements have a single stable isotope] at low temperature, When the number of monolayers 2n within one superlattice (SL) unit cell is varied, anticrossings between phonons confined in the (GaX)-Ga-69 and (GaX)-Ga-71 layers an observed. We have used a planar bond-charge model to calculate the frequencies and intensities of the modes as a Function of layer thickness. For the Gap isotope SL's, we find that a simulation of isotopically mixed interface layers is in good agreement with the experiment, while the assumption of ideal interfaces does not reproduce the data well. Spectra from the GaAs isotope SL's an substantially broadened compared to the LO phonon width in bulk samples, thus allowing only a qualitative discussion of phonon-confinement effects. Predictions for GaSb isotope SL's, in which both Ga and Sb isotopes can be substituted, are given. Raman spectra of bulk GaAs with varying gallium-isotope ratio are also discussed. [S0163-1829(99)04019-9].
Authors: CHUMAKOV-AI-1993-PHYS-REV-LETT-V71-P2489
Record 18 of 20. Title: Photoemission-Study of Monolayer Co on Si(111) Surface Authors: Kim-B Kim-KJ Kang-TH Full source: APPLIED SURFACE SCIENCE 1999, Vol 152, Iss 1-2, pp 44-48Abstract: The interaction of monolayer Co with the Si(lll) surface is investigated by means of core-level and valence-band photoemission spectroscopy in the range of room temperature to 700 degrees C. Upon increasing the annealing temperature, several formations of silicides are observed. This ultra-thin layer upon annealing at 300-400 degrees C has electronic structure closely related to the metastable CsCl-type CoSi which was discovered by molecular beam epitaxy (MBE) grown onto the CoSi, template to a thickness of similar to 100 Angstrom. Further annealing up to 500 degrees C leads to the epsilon-CoSi-type electronic structure. Finally, the formation of CaF2-type CoSi2 is observed after annealing above 600 degrees C. They lead also to an island formation above 700 degrees C. (C) 1999 Elsevier Science B.V. All rights reserved.
Authors: MADER-KA-1993-PHYS-REV-B-V48-P4364
Record 19 of 20. Title: Mossbauer Reflectometry of Ultrathin Multilayer Zr(10 nm)/(Fe-57(1.6 nm)/Cr(1.7 nm)X26)/Cr(50 nm) Film Using Synchrotron-Radiation Authors: Andreeva-MA Irkaev-SM Semenov-VG Prokhorov-KA Salashchenko-NN Chumakov-AI Ruffer-R Full source: JOURNAL OF ALLOYS AND COMPOUNDS 1999, Vol 286, Iss 1-2, pp 322-332Abstract: Time-resolved nuclear resonant reflectivity from ultrathin multilayer Zr(10 nm)/[Fe-57(1.6 nm)/Cr(1.7 nm)x26]/Cr(50 nm) film at grazing incidence angles of synchrotron radiation has been investigated at the Nuclear Resonance Beamline of the European Synchrotron Radiation Facility. For interpretation of the results, complementary measurements of X-ray reflectivity and grazing incidence Moessbauer spectra of reflectivity and secondary electron yield are invoked. Peculiarities and depth-selectivity of the Moessbauer reflectometry method in energy and rime domain are compared. It is shown that using this method the information about top layers of the multilayer structure can be obtained. Computer fitting of the energy and time spectra shows the decreasing of the hyperfine magnetic field in the upper layers of investigated multilayer structure. (C) 1999 Elsevier Science S.A. All rights reserved.
Authors: TOELLNER-TS-1995-PHYS-REV-LETT-V74-P3475
Record 20 of 20. Title: Nuclear-Resonance Forward Scattering of X-Rays - Time and Space Picture Authors: Shvydko-YV Full source: PHYSICAL REVIEW B-CONDENSED MATTER 1999, Vol 59, Iss 14, pp 9132-9143Authors: DEAK-L-1996-PHYS-REV-B-V53-P6158