Energy spectra of quantum rings

Abstract

Experiments on a nearly spin degenerate two-dimensional electron system reveals unusual hysteretic and relaxational transport in the fractional quantum Hall effect (FQHE) regime. The magnetotransport near the transition between the spin-polarized and spin-unpolarized Image states is accompanied by a complicated series of hysteresis loops reminiscent of a classical ferromagnet. In conjunction with the hysteresis, magnetoresistance can either grow or decay logarithmically in time with remarkable persistence without saturation. These results can be understood in terms of anomalous domain dynamics associated with the spin transition or alternatively in terms of quantum Hall ferromagnet.