Evidence of radiation-driven Landau states in 2D electron systems: magnetoresistance oscillations phase shift

TL;DR

This paper explains the phase shift in microwave-induced magnetoresistance oscillations in high mobility 2D electron systems by modeling radiation-driven Landau states and their scattering dynamics, matching experimental observations.

Contribution

It introduces a scattering flight-time concept within the radiation-driven electron orbits model to explain the phase shift in magnetoresistance oscillations.

Findings

Exact match of calculated extrema and nodes with experimental data

Identification of a π/2 delay as the origin of the phase shift

Analysis of how radiation frequency and power affect minima positions

Abstract

We provide the ultimate explanation of one of the core features of microwave-induced magnetoresistance oscillations in high mobility two dimensional electron systems: the 1/4-cycle phase shift of minima. We start with the radiation-driven electron orbits model with the novel concept of scattering flight-time between Landau states. We calculate the extrema and nodes positions obtaining an exact coincidence with the experimental ones. The main finding is that the physical origin of the phase shift is a delay of $\frac{\pi}{2}$ of the radiation-driven Landau guiding center with respect to radiation, demonstrating the oscillating nature of the irradiated Landau states. We analyze the dependence of this minima on radiation frequency and power and its possible shift with the quality of the sample