Theory of the fractional microwave-induced resistance oscillations

TL;DR

This paper develops a comprehensive theoretical framework to explain microwave-induced resistance oscillations near fractional harmonics of cyclotron resonance in 2D electron gases, highlighting multiphoton and single-photon mechanisms.

Contribution

It introduces a systematic theory accounting for both multiphoton and single-photon processes affecting magnetoresistivity near fractional harmonics.

Findings

Dominance of distribution function changes due to multiphoton processes at well-separated Landau levels.

Single-photon mechanisms become significant at moderate magnetic fields.

The theory aligns with recent experimental observations.

Abstract

We develop a systematic theory of microwave-induced oscillations in magnetoresistivity of a 2D electron gas in the vicinity of fractional harmonics of the cyclotron resonance, observed in recent experiments. We show that in the limit of well-separated Landau levels the effect is dominated by a change of the distribution function induced by multiphoton processes. At moderate magnetic field, a single-photon mechanism originating from the microwave-induced sidebands in the density of states of disorder-broadened Landau levels becomes important.