MAGNETIZATION OF A DIFFUSIVE RING - BEYOND THE PERTURBATION-THEORY

Average persistent current over a set of diffusive metallic rings with fixed number of electrons is considered. We study the care in which t he phase breaking time is much greater than an inverse average interle vel distance, In such a case, many return events for an electron must be taken into account, As a result, one arrives at a nonperturbative p roblem for a cooperon mode fixed by an external magnetic field, This m ulti-cooperon problem has been considered previously by Altland et al. , [Europhys. Lett. 20, 155 (1992)] and in several following papers wit hin the framework of supersymmetric approach. Such an approach involve s very tedious calculations which were performed using a computer alge braic package. Here we solve the problem in question with the help of a replica trick, It is demonstrated that the replica trick in combinat ion with a proper analytical continuation in the replica space allows one to obtain the result in much more explicit way. (C) 1997 American Institute of Physics.