Spectrum of relaxation times for ising spin clusters in random fields |
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Authors: | G Ismail A -A Salem |
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Institution: | (1) Mathematical Department, Faculty of Science, Zagazig University, Zagazig, Egypt |
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Abstract: | Summary Exact results on the single-spin-flip Glauber dynamics of six-coupled random field Ising spins with the coordination number
of four are presented. Two distributions of random fields (RF), binary (BD) and Gaussian (GD) ones, are investigated. The
effects of the static magnetic field are discussed. In the zero-magnetic-field case, the number of diverging relaxation times
is equal to the number of energy minima minus one. This rule breaks in the presence of a magnetic field. The longest relaxation
times in the absence of the field verify the Arrhenius law with the energy barrier determined by the energy needed to invert
the ground-state spin configuration. At low temperature, according to the Arrhenius law, the spectrum of relaxation times
shows a two-peaked distribution on a logarithmic scale. In the GD case of RF, the energy barrier distribution is continuous,
while it is quasi-discrete in the BD case. |
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Keywords: | General theory and models of magnetic ordering |
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