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

Transport studies of a bent quantum Hall junction at integer filling factor nu show strongly insulating states (nu=1,2) at higher fields. In this paper we analyze the strongly insulating behavior as a function of temperature T and dc bias V(dc) 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 G similar to exp[-(T(0)/T)(1/2)] at lower T. The base temperature electric-field dependence shows I(epsilon)similar to exp[-(epsilon(0)/epsilon)(1/2)], consistent with one-dimensional (1D) variable-range hopping conduction. We observe almost identical behavior at nu=1 and nu=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 counterpropagating quantum Hall edges.