Nonequilibrium phenomena in high Landau levels

Abstract

Developments in the physics of 2D electron systems during the last decade revealed a new class of nonequilibrium phenomena in the presence of a moderately strong magnetic field. The hallmark of these phenomena is magnetoresistance oscillations generated by the external forces that drive the electron system out of equilibrium. The rich set of dramatic phenomena of this kind, discovered in high mobility semiconductor nanostructures, includes, in particular, microwave radiation-induced resistance oscillations and zero-resistance states, as well as Hall field-induced resistance oscillations and associated zero-differential resistance states. The experimental manifestations of these phenomena and the unified theoretical framework for describing them in terms of a quantum kinetic equation are reviewed. This survey also contains a thorough discussion of the magnetotransport properties of 2D electrons in the linear-response regime, as well as an outlook on future directions, including related nonequilibrium phenomena in other 2D electron systems.

Circular-Polarization-Dependent Study of Microwave-Induced Conductivity Oscillations in a Two-Dimensional Electron Gas on Liquid Helium

“…These discoveries have opened a prominent research area and triggered a large body of theoretical works. The universality of the effect of MIRO was proved by similar observations in hole systems [5] and in a nondegenerate 2D electron system formed on the free surface of liquid helium [6].It is very surprising that by now there is a great body of different theoretical mechanisms explaining MIRO which use quantum and classical effects (for a review, see [7]), but the origin of these oscillations is still under debate. Among these mechanisms there is a large group of models whose description is based on the concept of the photonassisted scattering off disorder which overcomes the selection rules existing for direct photon-induced transitions; direct transitions can be only between adjacent Landau levels: n ′ − n = ±1 .…”

Comment on “Theory of microwave-induced zero-resistance states in two-dimensional electron systems” and on “Microwave-induced zero-resistance states and second-harmonic generation in an ultraclean two-dimensional electron gas”

“…In contrast to microscopic MIRO theories [46], which link B 0 to the quantum scattering rate, B 0 = 2πm ⋆ /eτ q , Ref. 1 postulates "that the electron scattering is not important in the discussed phenomena at all " while providing no alternative explanation for the observed exponential dependence .…”

“…These experiments have demonstrated that the electron transitions are a combination of backscattering off disorder and absorption/emission of microwave quanta. As discussed numerous times [35][36][37][38][39][40][41][42][43][44][45][46], the observation of electron backscattering relies on the uniformity of the electric field within the bulk of the sample. Resonant mixing of MIRO and magneto-inter-subband resistance oscillations [47][48][49][50] further proves that MIRO is a bulk phenomenon.…”

Dynamics of quantal heating in electron systems with discrete spectra

“…In contrast to classical Joule heating, quantal heating leads to outstanding nonlinear transport properties of highly mobile 2D electrons, driving them into exotic nonlinear states in which voltage (current) does not depend on current 4 (voltage) 5 . Quantal heating also provides significant contributions to nonlinear effects at high driving frequencies -an important topic in contemporary research 6 .…”