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

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.