Magnetic resonance in amorphous iron-nickel alloys

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.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Year dc:date

2011

Author dc:creator

• Hou, Ming-Kang

Contributors dc:contributor

• Salamon, Myron B.

• magnetic resonance
• amorphous iron-nickel alloys
• ESR study
• paramagnetic transitions
• spin-glass transitions

Statement dc:rights

• 1984 Ming-Kang Hou

Language dc:language

en

Identifier

5259076

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/25317