Phase Transition in the Random Anisotropy Model

Abstract

The influence of a local anisotropy of random orientation on a ferromagnetic phase transition is studied for two cases of anisotropy axis distribution. To this end a model of a random anisotropy magnet is analyzed by means of the field theoretical renormalization group approach in two loop approximation refined by a resummation of the asymptotic series. The one-loop result of Aharony indicating the absence of a second-order phase transition for an isotropic distribution of random anisotropy axis at space dimension $d<4$ is corroborated. For a cubic distribution the accessible stable fixed point leads to disordered Ising-like critical exponents.