Microwave-Induced Suppression of Dissipative Conductivity and Its Shubnikov–de Haas Oscillations in Two-Dimensional Electron Systems: Effects of Dynamic Electron Localization and Plasma Reflection

Abstract

We present a model for microwave photoconductivity in two-dimensional electron systems (2DESs) in a magnetic field at microwave frequencies lower than the electron cyclotron frequency when the intra-Landau level (LL) transitions dominate. Using this model, we explain the effect of the decrease in the 2DES dissipative conductivity (and resistivity) and smearing of its Shubnikov-de Haas oscillations caused by microwave radiation observed recently. The model invokes the concept of suppression of elastic impurity scattering of electrons by the microwave electric field. We calculated the dependence of the 2DES conductivity associated with intra-LL transitions as a function of the radiation and cyclotron frequencies and microwave power. We take into account the effect of plasma reflection of microwaves from 2DES resulting in a distinction between the ac microwave electric field acting on electrons and that generated by a microwave source. The obtained dependences are consistent with the results of recent experimental observations.

Multiple and virtual photon processes in radiation-induced magnetoresistance oscillations in two-dimensional electron systems

“…1-4 Tremendous experimental [5][6][7][8][9][10][11][12][13][14] and theoretical [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] efforts have been devoted to study this exciting phenomenon and a general understanding of it has been reached. MIMOs emerge as the magnetoresistance R xx of the 2D system subject to a microwave radiation of frequency f = /2, exhibiting periodic oscillation as a function of the inverse magnetic field 1 / B.…”

“…6,10,13,14 Theoretically, the magnetoresistance drop was also anticipated 31,32 and referred to virtual photon effect, 31 or to microwave-induced dynamic localization. 32 Nevertheless, the range and the degree of this resistance descent remain unclear, and a unified theoretical treatment covering higher radiation intensity to demonstrate it together with multiphoton structures is desirable.…”

Microwave photoconductivity of a periodically modulated two-dimensional electron system: Striped states and overlapping Landau levels

“…with q j = q x e x + (ja + ∆a)/ℓ 2 B )e y , q ′ j = q x e x + (2k + (ja − ∆a)/ℓ 2 B )e y and kℓ 2 B from (23). The value ∆a is defined by the condition for energy conservation cos 2π…”

“…In a recent paper [20], we calculated the various conductivities in the regime ω/ω c ≪ 1 which, experimentally, for the case without periodic modulation potential, has shown a strong suppression of the Shubnikov de-Haas oscillations [21,22], in accordance with our calculation. Further theoretical work on this subject was done in [23,24].…”

Radiation-induced magnetoresistance oscillations in two-dimensional electron systems under bichromatic irradiation

“…Since the discovery of radiation induced magnetorersistance oscillations (RIMOs) and zeroresistance states (ZRS) in ultra-high mobility two-dimensional (2D) electron systems, 1,2,3,4 tremendous experimental 5,6,7,8,9,10,11,12,13,14 and theoretical 15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34 efforts have been devoted to study this exciting phenomenon and a general understanding of it has been reached. Under the influence of a microwave radiation of frequency f = ω/2π, the low-temperature magnetoresistance R xx of a 2D electron gas (EG), exhibits periodic oscillation as a function of the inverse magnetic field.…”