Issue
EPL
Volume 88, Number 5, December 2009
Article Number 57009
Number of page(s) 6
Section Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
DOI http://dx.doi.org/10.1209/0295-5075/88/57009
Published online 16 December 2009
EPL, 88 (2009) 57009
DOI: 10.1209/0295-5075/88/57009

Nonlinear $\mth{\sigma}$-model study of magnetic dephasing in a mesoscopic spin glass

A. A. Fedorenko and D. Carpentier

Laboratoire de Physique de l'Ecole Normale Supérieure de Lyon - 46, Allée d'Italie, 69007 Lyon, France, EU

David.Carpentier@ens-lyon.fr

received 22 July 2009; accepted in final form 16 November 2009; published December 2009
published online 16 December 2009

Abstract
We propose a nonlinear sigma-model for the description of quantum transport in a mesoscopic metallic conductor with magnetic impurities frozen in a spin glass phase. It accounts for the presence of both the corresponding scalar and magnetic random potentials. In a spin glass, this magnetic random potential is correlated between different realizations. As the strength of the magnetic potential is varied, this model describes the crossover between orthogonal and unitary universality classes of the nonlinear sigma-model. We apply this technique to the calculations of the correlation of conductance between two frozen spin configurations in terms of dephasing rates for the usual low-energy modes of weak-localization theory.

PACS
73.23.-b - Electronic transport in mesoscopic systems.
75.50.Lk - Spin glasses and other random magnets.
75.10.Nr - Spin-glass and other random models.

© EPLA 2009