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Studies on Magnetoresistance in Fe/In Magnetic Thin Films

Author: ZhangZhaoGang
Tutor: ChenPeng
School: Southwestern University
Course: Condensed Matter Physics
Keywords: Giant magnetoresistance multilayers granular film oscillation superparamagnetic spin
CLC: O482.5
Type: Master's thesis
Year: 2008
Downloads: 53
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Abstract


In this thesis, the development, matter and mechanism of several kinds of magnetoresistance effect are presented generally and briefly. Fe/In multilayers were prepared by DC magnetron sputtering method, and Fe/In granular films were fabricated by co-sputtering method. We introduced the fabrication, structual characteristic and measurement of all samples in detail. Atomic Force Microscope images were taken for the samples to investigate the variation of the surface morphology. The matter phase and the atom concentration with varying thickness in Fe/In granular films by X-Ray Photoelectron Spectroscopy （XPS）. The magnetic properties of the materials were measured by vibrating sample magnetometer （VSM）. Magnetoresistance （MR） was measured using the microresistance test system at different temperature. The MR were studied as varying the thickness of In layers and Fe layers. Then from the microstructure gained, the experimental MR data were given a reasonable and good fitting by the Langevin-like relation MR = MRFM + MRspmL（x）, and were analysed with the spin-relevant scattering theory and the argument of "interfacial loose spins" used by Slonczewski. The results of an extensive study of conduction mechanism and their magnetic properties in such Fe/In multilayers and granular films are presented. In short, the main works are listed as following:1) Fe/In multilayers were prepared by DC magnetron sputtering method.2) Atomic Force Microscope images were taken for the samples to investigate the variation of the surface morphology. The surface of the samples are rough.3) The magnitude of GMR was found to oscillate with a period about 1.3 nm when varying the thickness of In layers. when the In layers’ thickness is larger than a crucial thickness, the MR exhibits such anomalous temperature dependence that the MR value at high temperature is larger than that at low temperature. The MR with Fe layer thickness has a maximum.4) The GMR effect is composed of the low-field MR and the high-field MR. The low-field MR, which corresponds to ferromagnetic contribution MRfm. enhances as the temperature is lowered. The high-fteld MR mainly corresponds to superparamagnetic effect at the intermixed Fe/In interface. A reduction of the anomalous high-field MR effect with decreasing temperature was observed.5) Fe/In granular films were prepared by co-sputtering method. The results of magnetoresistance effect and magnetic property in Fe14In86 nano-granular film indicates that the isolated Fe particles are pancake-like instead of spherical. X-Ray Photoelectron Spectroscopy （XPS） shows that the In nanoparticles and inner Fe nanoparticles primarily contained simple substance form and the Fe nanoparticles were partly oxidized at the surface of Fe/In granular films.

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CLC: > Mathematical sciences and chemical > Physics > Solid State Physics > Solid nature of the > Magnetic properties
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