Replica symmetry breaking and the renormalization group theory of the weakly disordered ferromagnet
Abstract
We study the critical properties of the weakly disordered $p$component ferromagnet in terms of the renormalization group (RG) theory generalized to take into account the replica symmetry breaking (RSB) effects coming from the multiple local minima solutions of the meanfield equations. It is shown that for $p < 4$ the traditional RG flows at dimensions $D=4\epsilon$, which are usually considered as describing the disorderinduced universal critical behavior, are unstable with respect to the RSB potentials as found in spin glasses. It is demonstrated that for a general type of the Parisi RSB structures there exists no stable fixed points, and the RG flows lead to the {\it strong coupling regime} at the finite scale $R_{*} \sim \exp(1/u)$, where $u$ is the small parameter describing the disorder. The physical concequences of the obtained RG solutions are discussed. In particular, we argue, that discovered RSB strong coupling phenomena indicate on the onset of a new spin glass type critical behaviour in the temperature interval $\tau < \tau_{*} \sim \exp(1/u)$ near $T_{c}$. Possible relevance of the considered RSB effects for the Griffith phase is also discussed.
 Publication:

Journal of Physics A Mathematical General
 Pub Date:
 September 1995
 DOI:
 10.1088/03054470/28/18/010
 arXiv:
 arXiv:condmat/9502061
 Bibcode:
 1995JPhA...28.5183D
 Keywords:

 Condensed Matter
 EPrint:
 32 pages, Latex