Spin-related phenomena in two-dimensional hopping regime in magnetic field

TL;DR

This paper investigates spin-related phenomena in two-dimensional hopping conduction under magnetic fields, deriving kinetic equations and calculating conductivities that reveal complex magnetic field-dependent behaviors.

Contribution

It introduces a theoretical framework for coupled spin and charge dynamics in the hopping regime, including derivation of kinetic equations and calculation of generalized conductivities.

Findings

Conductivities change sign with magnetic field for all spin relaxation times.

Different regimes of spin and charge dynamics depend on the relation between relaxation and hopping times.

Theoretical predictions supported by numerical simulations.

Abstract

The spin relaxation time of localized charge carriers is few orders of magnitude larger than that of free electrons and holes. Therefore mutual conversion of spin polarization, charge current and spin current turns out to be underlined in the hopping conductivity regime. We reveal different regimes of the coupled spin and charge dynamics depending on the relation between spin relaxation time and the characteristic hopping time. We derive kinetic equations to describe electrical spin orientation, dc spin-Hall effect, and spin galvanic effect in the transverse magnetic field. The generalized macroscopic conductivities describing these effects are calculated using percolation theory supported by numerical simulation. The conductivities change the sign at least once as functions of magnetic field for all values of the spin relaxation time.