Measurement of Coulomb drag between Anderson insulators

TL;DR

This study measures Coulomb drag between two insulating amorphous silicon-niobium films, revealing a limited parameter range for sizable transresistivity and consistency with Efros-Shklovskii Anderson insulators under specific assumptions.

Contribution

It provides the first measurement of Coulomb drag between Anderson insulators and analyzes its temperature dependence.

Findings

Sizable transresistivity observed in limited conditions

Temperature dependence aligns with Efros-Shklovskii model

Layer properties inferred from transresistivity measurements

Abstract

We report observations of the Coulomb drag effect between two effectively 2-d insulating a-Si_{1-x}Nb_{x} films. We find that there only exist a limited range of experimental parameters over which we can measure a sizable linear-response transresistivity (\rho_{d}). The temperature dependence of \rho_{d} is consistent with the layers being Efros-Shklovskii Anderson insulators provided that a 3-d density of states and a localization length smaller than that obtained from the DC layer-conductivity are assumed.