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Title:Magnetic resonance in amorphous iron-nickel alloys
Author(s):Hou, Ming-Kang
Doctoral Committee Chair(s):Salamon, Myron B.
Department / Program:Physics
Subject(s):magnetic resonance
amorphous iron-nickel alloys
ESR study
paramagnetic transitions
spin-glass transitions
Abstract:An ESR study on amorphous FexNi80-xP20 alloys was performed at 1.1 Ghz and 9.3 GHz, where x=8, 10, and 16. Fe8Ni72P20 and Fe10Ni70P20 show paramagnetic to spin-glass transitions, while Fe16N~4P20 shows paramagnetic to ferromagnetic and ferromagnetic to spin-glass transitions. The lineshape, at both frequencies, undergoes a progressive distortion as the temperature is reduced. We use an improved dynamical model to fit the distorted lineshapes and demonstrate that there is a tendency for the relaxation rate to vanish as is approached. In the Tf spin-glass regime, we also find a shift in resonance position, in addition to the dynamical one, which is due to the existence of a static anisotropy field in the spin-glass state. The anisotropic energy K(T) is found to be proportional to (I-T/Tf). The relaxation rate can be fitted to a power-law and an Arrhenius Law temperature behaviors, however only power-law fitting gives reasonable fitting values, which indicates that the phase transition model is better able to explain the spin-glass transition phenomena.
Issue Date:1984
Genre:Dissertation / Thesis
Rights Information:1984 Ming-Kang Hou
Date Available in IDEALS:2011-06-07
Identifier in Online Catalog:5259076

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