LOW-TEMPERATURE BEHAVIOR OF RANDOM-ANISOTROPY MAGNETS

An improved computer annealing algorithm has been used to study the low-energy states of magnets with strong random anisotropy on simple-cubic lattices. For classical Heisenberg spins with isotropically random uniaxial anisotropy, the ferromagnetic correlations at T=0 can be described by a scaling exponent of about 0.2 and a correlation length of about 10 lattice units. The ground-state energy E0 is (-1.118 0.003)J. For XY spins with random p-fold anisotropy, the ground states are ferromagnetic, with magnetizations of 0.45 0.02, 0.715 0.015, and 0.843 0.006, for p=2, 3, and 4, respectively, and the values of E0/J are -1.5075 0.0015, -2.229 0.003, and -2.543 0.002. © 1990 The American Physical Society.