Symmetry breaking for ratchet transport in presence of interactions and magnetic field

TL;DR

This paper investigates how electron-electron interactions and magnetic fields influence microwave-induced ratchet transport in a two-dimensional electron system, revealing mechanisms for magnetic field asymmetry and symmetry breaking.

Contribution

It introduces a detailed analysis of magnetic field asymmetries in ratchet currents considering electron interactions, highlighting new effects of combined interactions and magnetic fields.

Findings

Magnetic field asymmetric ratchet current can arise from Hall drift and symmetry breaking.

Asymmetry diminishes in the weak interaction limit.

Discussion of recent experimental observations on nanostructures.

Abstract

We study the microwave induced ratchet transport of two-dimensional electrons on an oriented semidisk Galton board. The magnetic field symmetries of ratchet transport are analyzed in presence of electron-electron interactions. Our results show that a magnetic field asymmetric ratchet current can appear due to two contributions, a Hall drift of the rectified current that depends only weakly on electron-electron interactions and a breaking of the time reversal symmetry due to the combined effects of interactions and magnetic field. In the latter case, the asymmetry between positive and negative magnetic fields vanishes in the weak interaction limit. We also discuss the recent experimental results on ratchet transport in asymmetric nanostructures.