Relaxation oscillations in a bistable quantum Hall system

摘要

Quantum Hall systems can show a bistability in the hysteresis of the breakdown. We realized a relaxation oscillator based on a quantum-Hall device with Corbino geometry. Investigations of the performance of such an oscillator revealed an increase of the hysteresis of the current―voltage curve of the device in comparison with the width of hysteresis at dc voltages. By direct measurements of the hysteresis of the current―voltage curve at different frequencies, we found a marked increase of the breakdown hysteresis at low frequencies of some Hz. We explain the observed dynamical enhancement of the breakdown hysteresis applying an electron heating model with a background (delocalization-related) component of conductivity, which decreases with increasing frequency, indicating a more effective localization already at low frequencies.