Microwave photoconductivity of a two-dimensional electron gas: Mechanisms and their interplay at high radiation power

Abstract

We develop a systematic theory of microwave-induced oscillations in the magnetoresistivity of a two-dimensional electron gas, focusing on the regime of strongly overlapping Landau levels. At linear order in microwave power, two novel mechanisms of the oscillations ("quadrupole" and "photovoltaic") are identified, in addition to those studied before ("displacement" and "inelastic"). The quadrupole and photovoltaic mechanisms are shown to be the only ones that give rise to oscillations in the nondiagonal part of the photoconductivity tensor. In the diagonal part, the inelastic contribution dominates at moderate microwave power, while at elevated power the other mechanisms become relevant. We demonstrate the crucial role of feedback effects, which lead to a strong interplay of the four mechanisms in the nonlinear photoresponse and yield, in particular, a nonmonotonic power dependence of the photoconductivity, narrowing of the magnetoresonances, and a nontrivial structure of the Hall photoresponse. At ultrahigh power, all effects related to the Landau quantization decay due to a combination of the feedback and multiphoton effects, restoring the classical Drude conductivity.

Microwave-induced Hall resistance in bilayer electron systems

“…The two main competing microscopic mechanisms for oscillating photoresistance are the "displacement" mechanism, which accounts for spatial displacement of electrons along the applied dc field under scattering-assisted microwave absorption, 4,5 and the "inelastic" mechanism, owing to an oscillatory contribution to the isotropic part of the electron distribution function. 6,7 Such a consideration describes the periodicity and phase of MIRO's observed in experiments.…”

“…12,13 The MWinduced Hall resistance R xy = R xy − R Theoreticians, however, have started to work on MWinduced Hall resistance, suggesting several microscopic mechanisms that describe how R xy is affected by an ac field. 7,14 Dissipative resistivity ρ xx (B) = ρ xx (−B), whose change at low temperatures is governed mostly by the inelastic mechanism, 6,7 remains an even function under magneticfield reversal. In contrast, the mechanisms responsible for Hall resistivity lead to both odd-and even-symmetry contributions in R xy .…”

Scaling of thermoelectric voltage induced by microwave radiation at the boundary between two-dimensional electron systems

“…In response to microwave radiation and dc bias, strongly nonlinear transport [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] that gives rise to unusual states [19][20][21][22][23][24] has been reported in two-dimensional systems of electrons in high magnetic field. There has also been great interest in the nonlinear response of quantum ballistic constrictions, where the effects of quantum interference, spatial dispersion, and electron-electron interactions play crucial roles.…”

Phase study of oscillatory resistances in microwave-irradiated- and dark-GaAs/AlGaAs devices: Indications of an unfamiliar class of the integral quantum Hall effect

“…The results therefore suggest one new class of IQHE, as they provide insight into the origin of oscillatory variations in the Hall effect, and their evolution into Hall plateaus, in the low-B large-ν regime of the radiationinduced zero-resistance states in the photoexcited high mobility 2DES. [6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49] Transport studies of photo-excited two-dimensional electron systems have become a topic of interest following the discovery of novel radiation-induced zeroresistance states in the GaAs/AlGaAs system at high filling factors. [6,16] The characteristic field B f for these zero-resistance states and associated magneto-re...…”