Possibility of a continuous phase transition in random-anisotropy magnets with a generic random-axis distribution

Article

关键词: MEAN-FIELD THEORY;    LONG-RANGE ORDER;    CRITICAL-BEHAVIOR;    RENORMALIZATION-GROUP;    CRITICAL EXPONENTS;    ISING-MODEL;    EPSILON-EXPANSION;    SPIN SYSTEMS;    DEFECTS;    DIMENSIONALITY;   

DOI  :  10.1103/PhysRevB.101.064402

来源: SCIE

【 摘 要 】

We reconsider the problem of the critical behavior of a three-dimensional O(m) symmetric magnetic system in the presence of random-anisotropy disorder with a generic trimodal random-axis distribution. By introducing n replicas to average over disorder it can be coarse grained to a phi(4) theory with an m x n component order parameter and five coupling constants taken in the limit of n -> 0. Using a field theory approach we renormalize the model to two-loop order and calculate the beta functions within the epsilon expansion and directly in three dimensions. We analyze the corresponding renormalization group flows with the help of the Pade-Borel resummation technique. We show that there is no stable fixed point accessible from physical initial conditions whose existence was argued in previous studies. This may indicate the absence of a long-range ordered phase in the presence of random-anisotropy disorder with a generic random-axis distribution.

【 授权许可】

Free