Hopping conduction in strongly insulating states of a diffusive bent quantum Hall junction

TL;DR

This study investigates the insulating behavior in a bent quantum Hall junction, revealing a crossover from activated to variable-range hopping conduction mechanisms as temperature decreases, with conductance independent of bulk spin states.

Contribution

It provides a detailed analysis of the conduction mechanisms in a bent quantum Hall junction, highlighting the role of 1D variable-range hopping and the insensitivity to bulk spin states.

Findings

Crossover from activated to variable-range hopping with decreasing temperature

Electric field dependence consistent with 1D variable-range hopping

Conductance behavior similar at filling factors 1 and 2

Abstract

Transport studies of a bent quantum Hall junction at integer filling factors show strongly insulating states at higher fields. In this paper we analyze the strongly insulating behavior as a function of temperature T and dc bias V, in order to classify the localization mechanisms responsible for the insulating state. The temperature dependence suggests a crossover from activated nearest-neighbor hopping at higher T to variable-range hopping conduction at lower T. The base temperature electric field dependence is consistent with 1D variable-range hopping conduction. We observe almost identical behavior at filling factors 1 and 2, and discuss how the bent quantum Hall junction conductance appears to be independent of the bulk spin state. Various models of 1D variable-range hopping which either include or ignore interactions are compared, all of which are consistent with the basic model of disorder coupled counter-propagating quantum Hall edges.