Absence of irreversibility in isotropic Heisenberg spin-glasses: Anisotropy effects

On the basis of a numerical study of a mean-field free-energy surface, the authors propose that an isotropic Heisenberg spin-glass has no irreversibility. The field-cooled and zero-field-cooled states are the same and magnetic hysteresis is absent. The authors show how Dzyaloshinsky-Moriya and uniaxial anisotropy effects lead to irreversibility. Hysteresis loops exhibit sharp jumps at constant field only when both microscopic anisotropy and a ferromagnetic tendency are present. © 1983 The American Physical Society.