Resonant Phonon Scattering in Quantum Hall Systems Driven by dc Electric Fields

TL;DR

This paper investigates how dc electric fields influence resonant phonon scattering in quantum Hall systems, revealing significant modifications in phonon resonances, the emergence of zero-differential resistance states, and the interplay between phonon scattering and impurity effects.

Contribution

It demonstrates the impact of dc electric fields on phonon resonances and introduces the observation of dc-induced zero-differential resistance states in quantum Hall systems.

Findings

dc electric fields modify phonon resonances from maxima to minima and back

resonances are enhanced in non-linear dc response and detectable at low temperatures

observation of dc-induced zero-differential resistance state and a resistance maximum near the speed of sound

Abstract

Using dc excitation to spatially tilt Landau levels, we study resonant acoustic phonon scattering in two-dimensional electron systems. We observe that dc electric field strongly modifies phonon resonances, transforming resistance maxima into minima and back into maxima. Further, phonon resonances are enhanced dramatically in the non-linear dc response and can be detected even at low temperatures. Most of our observations can be explained in terms of dc-induced (de)tuning of the resonant acoustic phonon scattering and its interplay with intra-Landau level impurity scattering. Finally, we observe a dc-induced zero-differential resistance state and a resistance maximum which occurs when the electron drift velocity approaches the speed of sound.