Giant microwave photoresistivity in a high-mobility quantum Hall system

TL;DR

This paper reports a giant microwave photoresistivity peak in a high-mobility 2D electron system, appearing near the second harmonic of cyclotron resonance at high microwave frequencies, exceeding previous observations and challenging existing theories.

Contribution

It presents the discovery of a new, extremely strong microwave photoresistivity effect near the second harmonic of cyclotron resonance, not explained by current models.

Findings

Giant microwave-induced resistivity peak observed

Peak appears only near second harmonic of cyclotron resonance

Peak strength exceeds microwave-induced resistance oscillations

Abstract

We report the observation of a remarkably strong microwave photoresistivity effect in a high-mobility two-dimensional electron system subject to a weak magnetic field and low temperature. The effect manifests itself as a giant microwave-induced resistivity peak which, in contrast to microwave-induced resistance oscillations, appears only near the second harmonic of the cyclotron resonance and only at sufficiently high microwave frequencies. Appearing in the regime linear in microwave intensity, the peak can be more than an order of magnitude stronger than the microwave-induced resistance oscillations and cannot be explained by existing theories.