bluuebunny/crossref_metadata_2025_split huggingface dataset:
Perpendicular Magnetoresistance of Microstructured Pillars in Fe/Cr Magnetic Multilayers
Authors: Gijs M.A.M. , Lenczowski S.K.J. , Giesbers J.B. 
Published: September 2012

ABSTRACTWe have fabricated pillar-like microstructures of high vacuum sputtered Fe/Cr Magnetic Multilayers and measured the giant magnetoresistance effect in the configuration where the measuring current is perpendicular to the film plane from 4.2 K to 300 K. At 4.2 K we find a magnetoresistance of 108 % for multilayers with a Fe thickness of 3 nm and a Cr thickness of 1 nm. The pronounced temperature dependence of the perpendicular magnetoresistance is studied for samples with different Cr thicknesses and tentatively explained by electron-Magnon scattering. The low-temperature data are compared with existing low-temperáture models.
Studies of Exchange Coupling in Fe (001) Whisker/Cr/Fe Structures using BLS and Rheed Techniques.
Authors: Heinrich B. , From M. , Cochran J.F. , Liao L. X. , Celiński Z. , Schneider C.M. , Myrtle K. 
Published: September 2012

ABSTRACTThe conditions for an almost perfect growth of smooth Cr (001) films on an iron whisker substrate have been investigated by means of reflection high energy electron diffraction (RHEED). The exchange interaction between 20 Monolayer thick Fe (001) films separated from a bulk whisker Fe (001) substrate by a variable number of Cr (001) Monolayers (ML) has been investigated by means of Brillouin light scattering experiments (BLS). These experiments show unambiguously that the exchange coupling strength between the iron film and the iron whisker can be described by a short wavelength oscillatory term superposed on a slowly varying antiferromagnetic background. The BLS data enabled one to separate the bilinear and the biquadratic contributions to the antiferromagnetic exchange coupling terms. Both the bilinear and the biquadratic coupling strengths exhibited a short period oscillatory dependence on the Cr interlayer thickness (∼2 Monolayers). Maxima in the bilinear antiferromagnetic coupling strength occur for an odd number of Cr Monolayers. This observation is not in agreement with first principles calculations. The first phase inversion has been found to occur between 4 and 5 ML of Cr.
Direct Evidence of Biquadratic Coupling in multilayers by Neutron Scattering Experiments.
Authors: Andrieu Stéphane , Hennion Martine , Piecuch Michel 
Published: September 2012

ABSTRACTWe present small angle neutron scattering experiments on (001) Fe/Ir superlattices. A short period oscillated coupling is observed. However, antiferro and ferromagnetic peaks are simultaneously measured on neutron diagram, which cannot be simply explained. A biquadratic coupling model is proposed to account for this behaviour.
Effect of Hybridization on Exchange Coupling in Magnetic Multilayers
Authors: Mathon J. , Villeret M.A. , Mander J.M. , Edwards D.M. , Muniz R.B. 
Published: September 2012

ABSTRACTAn earlier theory of the exchange coupling between two ferromagnets separated by a nonmagnetic transition metal spacer was based on size quantization of the electron energies in the spacer. It is now generalized to include the effect of hybridization between the conduction and d bands both in the ferromagnet and in the spacer. The new theory thus unifies the approach based on coupling via d electrons, valid for transition metal spacers, with RKKY-type theories for noble and simple metals which rely on coupling via conduction electrons. The theory is applied to calculate the period and strength of the long-period oscillatory coupling in (001) CO/Cu trilayer.
Giant Magnetoresistance and Soft Magnetic Properties of NiFeCo/Cu Multilayers
Authors: Tsunashima S. , Jimbo M. , Kanda T. , Goto S. , Uchiyama S. 
Published: September 2012

ABSTRACTGiant Magnetoresistance (GMR) and soft magnetic properties together with their structural characteristics were investigated for Ni66Fe16Co18/Cu Multilayers. The Multilayers were prepared by the conventional rf sputtering method on glass or Si substrates using various buffer layers including Fe, NiFeCo, NiFe and CoZr. Although Most of the multilayers exhibited (111) preferred orientation, Fe buffered multilayers showed a considerable (200) X-ray diffraction peak at Cu thicknesses around 1 nm and 2.2 nm which corresponded to the peak positions of GMR. By using fee or amorphous underlayers the (200) diffraction intensity decreased while antiferromagnetic coupling strength was much reduced. Cross-sectional transmission electron micrograph revealed that the (100) oriented multilayer was grown on the (100) oriented Fe underlayer. By controlling the crystal orientation and the layer structure, significantly large magnetoresistance ratio of more than 10 % can be achieved in a field as low as 30 Oe.
Combined Spin Valve and Anisotropic Magnetoresistance in NiFe/Cu/NiFe Layered Thin Films
Authors: Rijks Th.G.S.M. , Coehoorn R. , De Jonge W.J.M. 
Published: September 2012

ABSTRACTWe present a theoretical study of the combined effect of spin valve and anisotropie magnetoresistance in NiFe/Cu/NiFe layered thin films, using an extended form of the semiclassical Camley and Barnás Model for electron transport. The anisotropie magnetoresistance is treated by introducing spin-dependent anisotropie mean free paths in the NiFe layers. From calculations of both magnetoresistance effects as a function of NiFe and Cu thickness, we discuss the validity of a description of the combined effect in terms of a simple summation of spin valve and anisotropie Magnetoresistance.
Annealed Cu/Co/Cu/NïFe/Femn Spin Valves: Nanostructure and Magnetism
Authors: Meny C. , Jay J.P. , Panissod P. , Humbert P. , Speriosu V.S. , Lefakis H. , Nozieres J.P. , Gurney B.A. 
Published: September 2012

ABSTRACTMagnetic, Magnetotransport and structural properties of Cu/Co/Cu/NiFe/Femn spin-valve structures were studied before and after sequential annealing in the temperature range 240–360°C. Since no extended interdiffusion is observed, the overall deterioration of the magnetic and magnetoresistive properties of the spin valve is believed to originate from morphological and structural changes. In particular, annealing was found to decrease the magnetoresistive properties of Co as a result of structural changes within the Co layer and at the CO/Cu interface. These changes are accompanied by modifications of the magnetic properties. For annealing temperatures above 240°C, strong grain growth within the Co layer and increasing amount of fee Co explain the increased magnetic hardness of this layer.
Oscillations in Exchange Coupling in Co/Cu Multilayers Grown by MBE
Authors: Greig D. , Hall M.J. , Howson M.A. , Hickey B.J. , Walker M.J. , Xu J. 
Published: September 2012

ABSTRACTWe have observed oscillations with non-Magnetic spacer layer thickness in the saturation fields and characteristic exchange fields of CO/Cu Multilayers grown by MBE. The Specimens consisted of a set of samples in which the thickness of copper layers took a series of values between 5Å and 20Å, while the cobalt layer thickness was set at 15Å throughout. The Multilayers were grown epitaxially on GaAs (110) with Ge, Co (110) and Au in the buffer region, resulting in CO/Cu bilayers in the (111) orientation. Although oscillations were observed in these magnetic measurements, no oscillations were observed in the magnetoresistance itself. These observations are somewhat at odds with similar measurements made on samples prepared by sputtering. We conclude with a discussion involving exchange coupling, in-plane anisotropy and defects in the magnetic structure in an attempt to account for these conflicting results.
Magnetic Anisotropy in Epitaxial Ni/Cu (100) Thin Films
Authors: Bochi G. , Ballentine C. A. , Inglefield H. E. , Bogomolov S. S. , Thompson C. V. , Ohandley R. C. 
Published: September 2012

ABSTRACTEpitaxial Ni/Cu (001) films grown on Si (001) by Molecular Beam Epitaxy were studied in-situ using the Surface Magneto-optic Kerr Effect (SMOKE) and ex-situ with a Vibrating Sample Magnetometer (VSM). Perpendicular Magnetization is observed for Ni thicknesses 15 Å ≤ h ≤ 60 Å and fully in-plane magnetization for h ≥ 70 Å when the films are characterized in-situ. The reversal in magnetic anisotropy observed in-situ at 60 Å shifts to 125 Å when the films are exposed to air. 100 Å Ni films deposited on Cu1−x-Nix alloy substrates also show a reversal in magnetic anisotropy as x is changed. These results suggest that changes in magnetic anisotropy correlate with misfit strain accommodation.
Vanadium as Overlayer on Ag(001)
Authors: Nait-Laziz H. , Demangeat C. , Mokrani A. 
Published: September 2012

ABSTRACTThe electronic and magnetic structure of small vanadium clusters adsorbed on Ag (001) is studied as a function of the exchange integral J of the Hubbard Hamiltonian and cluster size with bcc structure. For each topological arrangement, the transition from nonmagnetic to magnetic order is characterized. As in the case of films (1 or 2 layers thick) epitaxially grown on Ag (001), antiferromagnetic coupling between V atoms is usually obtained. However, because the symmetry is lower in the present case, various magnetic configurations are displayed.
Strong Influence of Tb Concentration on Domain Structure and Kerr Effect of TbxFe1−x Thin Films
Authors: Florescu V. , Rau C. , Zheng N. J. 
Published: September 2012

ABSTRACTAmorphous TbFe films with perpendicular magnetic anisotropy are attracting wide attention as promising candidates for erasable high - density Magneto - optical recording and thermomagnetic printing. TbxFe1−x thin films with 0 ≤ × ≤ 0.37 are deposited on glass substrates using r.f. sputtering. The Magnetic remanent domain structures are studied at room temperature using the longitudinal and polar Kerr effect. Samples with 0 ≤ × ≤ 0.23 exhibit magnetic in-plane anisotropy, while samples with 0.26 ≤ × ≤ 0.37 possess uniaxial anisotropy with easy axis perpendicular to the film plane. The remanent domain structures depend strongly on Tb content. High remanence and high coercivity are found for samples with 0.27 ≤ × ≤ 0.34 which is confirmed by additional vibrating sample Magnetometer (VSM) Measurements.
Magnetic Properties and Crystal Structure of High Moment FeTaN Thin Films
Authors: Qiu G. , Haftek E. , Cates J. C. , Alexander C. , Barnard J. A. 
Published: September 2012

ABSTRACTHigh Moment single layer FeTaN films with excellent soft magnetic properties have been grown by high rate reactive dc magnetron sputtering. The best combination of properties (easy and hard axis coercivities < 1 Oe, saturation Magnetization > 1650 emu/cc, anisotropy field of 5 Oe, and initial permeability of 4800) are found in films containing ∼3.2 a/O Ta and ∼7.5 a/o N after 400°C annealing in a 200 Oe dc field for two hours. These properties are associated with a single phase, random, nanocrystalline structure consisting of a-Fe crystallites (grain size of ∼ 100Å) whose lattice is expanded by both Ta and N.
High-Field Giant Magnetoresistance in Co-Cu Superlattices
Authors: Barlett Darryl , Tsui Frank , Lauhon Lincoln , Mandrekar Tushar , Uher Ohrad , Clarke Roy 
Published: September 2012

ABSTRACTWe present evidence for a new type of giant magnetoresistance in (111) cobalt-copper superlattices with atomically smooth interfaces. We propose that the lowered dimensionality of the structure leads to an enhancement of the scattering of conduction electrons from paramagnetic interfaces obeying a Langevin-like saturation at very high fields, well beyond the switching field of the Co layers. The findings help to explain similarities in magnetotransport behavior with recently reported granular systems as well as differences with antiferromagnetically coupled Multilayers.
Development of Crystallographic Texture in RF Sputter Deposited CoCrTa/Cr Thin Films
Authors: Feng Y. C. , Laughlin D. E. , Lambeth D. N. 
Published: September 2012

ABSTRACTIt is well known that Cr sputtered on glass or NiP/Al substrates has either the (002) or (110) crystallographic texture (depending on the substrate temperature) and that the Co-alloy layers which are deposited on the Cr underlayers have either the (1120) or (1011) textures respectively. However, the dependence of the crystallographic textures on other sputtering parameters is not clear. We report here on the study of the dependence of crystallographic textures of CoCrTa/Cr films on substrate bias. It is found that both Cr (110) and Cr (002) textures can form at elevated temperature, depending on the substrate bias. The development of the crystallographic texture is discussed with a Model. It is also found that the epitaxy of CoCrTa layer depends on the sputtering conditions of both the Cr and the CoCrTa layers. The extrinsic magnetic properties (such as He, S and S*) of thin films with various textures are also presented. By controlling the sputtering procedure, the effects of crystallographic textures on magnetic properties were separated from the effects of film Morphology.
The Influence of Quantizing Magnetic Field on The Magnetic Susceptibilities in Ultra Thin Films of Dilute Magnetic Materials
Authors: Ghatak Kamakhya P , Biswas S. N. 
Published: September 2012

ABSTRACTIn this paper we have studied the dia and paramagnetic susceptibilities of the holes in ultrathin films of dilute magnetic materials in the presence of a quantizing magnetic field and compared the same with that of the bulk specimens under magnetic quantization for the purpose of relative comparison. It is found, taking Hg1−xMnxTe and Cd1−xMnxSe as examples, that both the susceptibilities increase with decreasing film thickness and increasing surface concentration in oscillatory Manners. The numerical values of the susceptibilities in ultrathin films of dilute magnetic materials are greater than that of the bulk and the theoretical analysis is in agreement with the experimental data as reported elsewhere.
Giant Magnetoresistance in Single Layer and Multilayer Phase Separating Alloy Films
Authors: Hossain S. , Waknis A. , Seale D. , Tan M. , Parker M.R. , Barnard J.A. 
Published: September 2012

ABSTRACTThe phenomenon of giant magnetoresistance (GMR), previously measured only in multilayer films comprising ferromagnetic layers separated by nonmagnetic spacers, has recently been observed in single layer ‘granular’ alloy thin films prepared by cosputtering a ferromagnet and a nonmagnet which tend to phase separate (cluster) under equilibrium conditions. We have systematically studied the magnetoresistance of two new phase separating GMR systems (Ni66Fe16Co18-Ag and Co9oFelo-Ag) both of which exhibit large room temperature GMR (>11% and >14%, respectively). We have also attempted to influence the details of the field dependence of the magnetoresistance in the previously studied Co-Ag system by employing novel processing methods including interrupted sputtering and layering of the Co-Ag alloy with Cu spacers.
A Microstructural Study of Iron Carbides Formed by Plasma-Enhanced Chemical Vapor Deposition (50–800 nm Thick)
Authors: Siriwardane H. , James W.J. , Pringle O.A. , Newkirk J.W. 
Published: September 2012

Thin Mirror-like iron carbide films were prepared by introducing iron pentacarbonyl [Fe(CO)5] and hydrogen [H2] into a glow discharge. The deposition temperatures were varied from 200–500°C. The iron to carbon ratios of the resulting films were controlled by adjusting the gas flow ratios. The Microstructure and phase transformations occurring in these films were studied before and after annealing at 400°C for four hrs. Characterization techniques used included x-ray diffraction, electron diffraction, Auger spectroscopy and atomic force Microscopy.X-ray diffraction data of plasma-deposited films on glass substrates maintained at 400°C showed the presence of only Fe3C. However, the x-ray diffraction data of films on carbon coated glass, and transmission electron microscopy selected area diffraction patterns of films on carbon coated copper grids indicated the presence of a second phase, the closely related Metastable Fe7C3, as well as small amounts of Fe3O4. Atomic force microscopy of crystallites on the surface of films deposited at 400°C and annealed at 400°C for four hours revealed a periodic structure of oblate spheroids. The Measured spacings and angle, when compared to projected models of high reticular density planes, suggested the surface to have a structure corresponding to that of bulk FesC or Fe3C or Fe7C3. However the data were not of sufficient quality to unambiguously determine such.
Dynamical Scattering of Polarized Neutrons by Thin Magnetic Films
Authors: Nunez V. , Majkrzak C.F. , Berk N.F. 
Published: September 2012

ABSTRACTUsing Larmor precession as a clock, Buttiker1 identified theoretical times for the scattering of particles from an opaque slab coincident with a magnetic field. The subsequent model generated interesting predictions for the influence of opaque regions on the magnetic polarization of the transmitted and reflected beams. Previous attempts to verify these predictions were unable to do so unambiguously2. Here, Biittiker's formulae are extended to more general geometries. An experiment has been devised to test the theory by measuring neutron beam polarization in both reflection from and transmission through magnetic films below the critical angle for external reflection.
Structural Characterization of Thin Co/Cu Superlattices
Authors: Smith David J. , Modak A.R. , Parkin S.S.P. 
Published: September 2012

ABSTRACTHigh-resolution electron microscopy has been used to characterize the microstructure of thin CO/Cu Metallic Multilayers grown on Si (100) substrates by dc magnetron sputtering. The nature of the buffer layer between the silicon wafer and the multilayer had a significant effect on the structural integrity of the Multilayer. An increase in grain size was observed as a function of Cu layer thickness, with grain sizes typically being at least 3–4 times the bilayer period. A high degree of structural ordering was observed in superlattices comprised of thicker Cu layers with large grains often spanning the complete multilayer stack. Complementary Magnetic Measurements enabled the microstructure to be related to the oscillatory exchange coupling and large magnetoresistance exhibited by these thin magnetic films.
Modification of Magnetic Coupling in Antiferromagnetically Coupled Bilayers Due to the Existence of Ferromagnetic Pin Holes.
Authors: Bobo J.F. , Fischer H. , Piecuch M. 
Published: September 2012

ABSTRACTWe have calculated numerical simulations and analytical solutions of the influence of a pin hole on the magnetization curves of multilayer systems. The Magnetization curves we obtained can be described by a biquadratic coupling model and are close to the experimental curves.
Spin Configurations and the Dynamic Response of Antiferromagnetically Coupled Systems
Authors: Nörtemann F.C. , Stamps R.L. , Camley R.E. 
Published: September 2012

ABSTRACTWe present a calculation of spin waves in coupled multilayered structures which is based on exact evaluation of both exchange and dipolar fields. The ground state spin configuration in antiferromagnetically coupled multilayers can differ significantly from the uniformly canted ground state usually assumed. This non-uniform ground state is found to radically alter the character of the spin wave modes and sometimes lead to a strong localization of the wave to the outermost magnetic films of the Multilayer.
Magnetization Loops in Fe/Ag/Fe/Ni (001) Structures
Authors: Heinrich B. , Celiński Z. , Konno H. , Arrott A. S. , Rührig M. , Hubert A. 
Published: September 2012

ABSTRACTThe lattice reconstructed bec Ni (001) in Fe/Ni (001) ultrathin layers allows one to engineer films in which the in-plane 4-fold anisotropies and coercive fields can be varied and adjusted according to specific requirements. Magnetization reversals have been studied in layered structures of Fe/Ag/Fe/Ni (001). For Ag (001) interlayers thicker than 13 ML Magnetization reversal can proceed in two steps. In these samples the minor loops switch the magnetization of the Fe (001) layer from the parallel to the antiparallel configurations with respect to the magnetic moment of the Fe/Ni film. Such Minor loops exhibit a rectangular behavior with switching fields of 15–25 Oe. The lattice transformed Fe/Ni layers could be useful in spin-valve structures.
Magneto Optical Kerr Spectroscopy as a Probe of Chemical Ordering in CoPt
Authors: Harp G. R. , Weiler D. , Rabedeau T. A. , Farrow R. F. C. , Marks R. F. 
Published: September 2012

AbstractWe demonstrate that the photon energy dependence of the polar Kerr effect can be used as a sensitive probe of chemical ordering effects in binary intermetallic alloys. We demonstrate this effect in the Co50Pt50 alloy, which is known to have a Ll0 phase (critical temperature ∼825°C). Kerr spectra of the ordered and disordered phases of the Co50Pt50 alloy composition differ drastically from each other and the ordered phase shows an unprecedented, new peak at 2.2eV photon energy. The intensity of this new peak correlates with the degree of chemical ordering and the magnetic anisotropy in these films.
Magneto-Optical Spectra of Copt3: Experiments and First Principles Calculations
Authors: Welter D. , Sticht J. , Harp G.R. , Farrow R.F.C. , Marks R.F. , Brandie H. 
Published: September 2012

ABSTRACTThe Magneto-optical Kerr effect of CoPt3 ordered compounds and alloys is investigated experimentally and analyzed theoretically using first principles band structure calculations.The calculations confirm the experimental results and allow for the first time a detailed, bandstructure based interpretation of the electronic transitions leading to the well known strong uv peak at around 4eV. This feature can be unambiguously attributed to Magneto-optical transitions within the Pt p and d bands.
Roughness and Magnetic Properties of Pt/CO Multilayered Films
Authors: Sumi S. , Kusumoto Y. , Teragaki Y. , Torazawa K. , Tsunashima S. , Uchiyama S. 
Published: September 2012

ABSTRACTMagnetic properties and roughness of sputter-deposited Pt/CO films strongly depend on preparation conditions such as rf input power, underlayers and their etching. Large coercivity was obtained by using suitable underlayers such as ZnO and adjusting input power higher for Co and lower for Pt. The coercivity in Pt/CO films seems to depend on the roughness of the surface and/or the layer interface as well as the perpendicular anisotropy.
Influence of Superlattice Potentials on Transport in magnetic multilayers
Authors: Zhang Shufeng , Levy Peter M. 
Published: September 2012

ABSTRACTWe discuss the effect of the superlattice potential on the magnetotransport properties of magnetic multilayers for current parallel and perpendicular to the plane of the layers. While quantum well states affect the Magnetotransport, they are not the primary origin of the giant Magnetoresistance observed in these materials for currents in the plane of the layers. In general, it is necessary to include both spin-dependent scattering and the effects of superlattice potentials in order to explain the magnetoresistance of multilayered structures.