Magnetic field anti-symmetry of photovoltaic voltage in evanescent microwave fields

TL;DR

This study explores how a microwave-induced photovoltaic voltage in a non-centrosymmetric 2D electron system exhibits magnetic field anti-symmetry and oscillations, explained by stationary orbital current models.

Contribution

It demonstrates the magnetic field anti-symmetry and oscillatory behavior of photovoltaic voltage in a 2D electron system with broken spatial symmetry under microwave radiation.

Findings

PV voltage is anti-symmetric with magnetic field.

PV voltage exhibits Shubnikov-de Haas like oscillations.

Experimental results align with a model involving stationary orbital currents.

Abstract

A two dimensional electron system without spatial inversion symmetry develops a sample specific dc voltage when exposed to a microwave radiation at low temperature. We investigate this photovoltaic (PV) effect, in the case where spatial symmetry is broken by an evanescent high-frequency potential. We measure the induced PV voltage in a ${\rm GaAs/Ga_{1-x}Al_{x}As}$ Hall bar at magnetic fields in the Tesla range. We find that in this regime the induced PV voltage is anti-symmetric with magnetic field, and exhibits regular Shubnikov-de Haas like oscillations. Our experimental results can be understood from a simple model, which describes the effect of stationary orbital currents caused by microwave driving.