Slow Dynamics in the 'Griffiths Phase' of the Two-Dimensional Ising Spin Glass

概要

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Slow dynamics in the ±J Ising model on a square lattice is studied by means of Monte Carlo simulation, in which the distribution function of(logarithms of) relaxation times, P(x) with x=ln τ, is obtained by analyzing individual spin auto-correlation functions one by one. At each temperature in the 'Griffiths phase', namely in the range above the spin-glass transition temperature T_c(=0) but below the Curie temperature of the corresponding pure ferromagnet T^<pure>_c, P(x) exhibits a characteristic crossover behavior at around x_c(=ln τ_c) which diverges toward T_c. The contributions to the branch x≲x_c are interpreted due to the ordinary critical slowing down process associated with T_c (critical dynamics). The behavior of P(x) at x≳x_c, on the other hand, is quite consistent with the picture of relaxation processes of large, rare clusters related to the expected Griffiths singularity at T^<pure>_c (cluster dynamics).
社団法人日本物理学会の論文
1995-11-15