Critical properties of random anisotropy magnets

TL;DR

This paper investigates the critical behavior of three-dimensional random anisotropy magnets, revealing how anisotropy distribution affects phase transitions and employing renormalization group theory to explain effective critical phenomena.

Contribution

It provides a theoretical analysis of critical properties in random anisotropy magnets, emphasizing the role of anisotropy distribution and effective critical behavior within the renormalization group framework.

Findings

Second order phase transition occurs with anisotropic distribution of axes.

No phase transition observed with isotropic distribution.

Effective critical behavior explains varied experimental and simulation results.

Abstract

The problem of critical behaviour of three dimensional random anisotropy magnets, which constitute a wide class of disordered magnets is considered. Previous results obtained in experiments, by Monte Carlo simulations and within different theoretical approaches give evidence for a second order phase transition for anisotropic distributions of the local anisotropy axes, while for the case of isotropic distribution such transition is absent. This outcome is described by renormalization group in its field theoretical variant on the basis of the random anisotropy model. Considerable attention is paid to the investigation of the effective critical behaviour which explains the observation of different behaviour in the same universality class.