Giant magnetoresistance in the variable range hopping regime

Theory Seminars

Speaker: Boris Spivak, University of Washington
Date & Time: January 27, 2014 12:00 - 13:00
Location: UBC, Hennings 318
Local Contact: Fei Zhou
Intended Audience: Graduate

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. I will discuss the existing experiments that show anomalously large magnetoresistance and the role spin degrees of freedom. Finally I will discuss a new spin memory mechanism of the magnetoresistance which can occur even at magnetic fields as small as fraction of Gauss.