Infinite susceptibility phase in random uniaxial anisotropy magnets

The leading terms in the magnetic equation of state are calculated for models with random fields and random uniaxial anisotropies for dimensionalities d<4. In the random anisotropy case we find a new low-temperature phase, in which the magnetization vanishes but the zero-field susceptibility is infinite, because of algebraically decaying correlations. No phase transition is found for the random field case. © 1980 The American Physical Society.