Mean-field theory of the random-axis model with infinite anisotropy

Abstract
The authors investigate the random anisotropy axis model (RAM) with additional cubic anisotropy in mean-field theory in the limit of infinite anisotropy. The model has in zero magnetic field and p dimensions a 2p-fold degenerate ferromagnetic ground state with a maximum number of possible order parameters. In finite fields the high-temperature phase becomes unstable along a critical line Hc(T). For low fields this line has the same field-temperature dependence as the de Almeida-Thouless line in spin glasses.