Breakdown of the [formula omitted] integer quantum Hall effect in the single particle and collective localization regimes

Abstract

We report large signal current–voltage characteristics measurements near the ν=1 integer quantum Hall plateau in a high mobility GaAs/AlGaAs sample that exhibits both single particle and collective localization. According to prior results, the central part of the ν=1 plateau corresponds to single particle localization and hence an Anderson insulator. In contrast, the two regions in the flanks of this Anderson insulator were associated with collective localization and were identified with the integer quantum Hall Wigner solid. We find that, at low temperatures and under large bias currents, both the Anderson insulator and integer quantum Hall Wigner solid have a sharp onset of conduction above a threshold. Furthermore, this threshold shows an approximately monotonic dependence on the filling factor across the boundary between the two localized phases. To our surprise, we find that these large signal characteristics do not clearly distinguish between the Anderson insulator and the integer quantum Hall Wigner solid.