Temperature Scaling Anomalies in Quantum Hall Plateau Transitions with Ultra-Short Period Lateral Superlattice

Abstract

The quantum Hall plateau transitions in GaAs/AlGaAs quantum wells with ultrashort (12 nm) period unidirectional potential modulation have been studied. For the magnetoresistance ρyy with probe current passed along the stripe, the transition peak width decreases very rapidly as temperature is lowered below 1 K, yielding substantially smaller values of localization length exponent than the canonical cases. By contrast, the ρxx peaks appear to conform with the canonical scaling behavior. The origin of this anomalous exponent is sought in the directionally correlated disorder characteristic in these systems.