Multiphoton processes at cyclotron resonance subharmonics in a 2D electron system under DC and microwave excitation

TL;DR

This study explores how microwave-induced multiphoton processes affect the differential resistivity oscillations in a 2D electron system under combined DC and microwave excitation, revealing power-dependent behavior linked to impurity scattering.

Contribution

It demonstrates the systematic change in oscillation count with microwave power and models the phenomena using the displacement mechanism of impurity scattering at cyclotron resonance subharmonics.

Findings

Oscillation count varies systematically with microwave power.

Microwave absorption/emission of N photons explains the observed behavior.

Differential resistivity oscillations are linked to impurity scattering mechanisms.

Abstract

We investigate a two-dimensional electron system (2DES) under microwave illumination at cyclotron resonance subharmonics. The 2DES carries sufficient direct current, $I$, that the differential resistivity oscillates as $I$ is swept. At magnetic fields sufficient to resolve individual Landau levels, we find the number of oscillations within an $I$ range systematically changes with increasing microwave power. Microwave absorption and emission of $N$ photons, where $N$ is controlled by the microwave power, describes our observations in the framework of the displacement mechanism of impurity scattering between Hall-field tilted Landau levels.