Giant magnetoresistance in the variable range hopping regime

TL;DR

This paper predicts a universal power law for localization length dependence on magnetic field in the strongly localized regime, explaining the large negative magnetoresistance observed experimentally through quantum interference effects.

Contribution

It introduces a universal power law dependence of localization length on magnetic field in the variable range hopping regime, supported by numerical simulations and theoretical analysis.

Findings

Power law dependence of localization length on magnetic field

Numerical simulations confirming the universality class

Discussion of experimental observations of large magnetoresistance

Abstract

We predict the universal power law dependence of localization length on magnetic field in the strongly localized regime. This effect is due to the orbital quantum interference. Physically, this dependence shows up in an anomalously large negative magnetoresistance in the hopping regime. The reason for the universality is that the problem of the electron tunneling in a random media belongs to the same universality class as directed polymer problem even in the case of wave functions of random sign. We present numerical simulations which prove this conjecture. We discuss the existing experiments that show anomalously large magnetoresistance. We also discuss the role of localized spins in real materials and the spin polarizing effect of magnetic field.