Coulomb Drag for Strongly Localized Electrons: Pumping Mechanism

TL;DR

This paper investigates Coulomb drag in strongly localized electrons, revealing a pumping mechanism driven by time correlations of site occupations that are overlooked in traditional models.

Contribution

It introduces a new understanding of Coulomb drag based on time correlations of site occupations, challenging conventional Miller-Abrahams assumptions.

Findings

Coulomb drag arises from time correlations of site occupations.

The mechanism explains voltage drops in passive layers during active layer current.

Traditional hopping resistance calculations neglect these correlations.

Abstract

The mutual influence of two layers with strongly loclized electrons is exercised through the random Coulomb shifts of site energies in one layer caused by electron hops in the other layer. We trace how these shifts give rise to a voltage drop in the passive layer, when a current is passed through the active layer. We find that the microscopic origin of drag lies in the time correlations of the occupation numbers of the sites involved in a hop. These correlations are neglected within the conventional Miller-Abrahams scheme for calculating the hopping resistance.