Microwave-induced nonlocal transport in a two-dimensional electron system

Abstract

We observe microwave induced nonlocal resistance in magnetotransport in single and bilayer electronic systems. The obtained results provide evidence for an edge state current stabilized by microwave irradiation due to nonlinear resonances. Our observation are closely related to microwave induced oscillations and zero resistance states in a two-dimensional (2D) electron system.A few years ago, a new class of the non-equilibrium phenomena was observed, when an ultrahigh mobility 2D electron gas, subjected to a weak magnetic field was also irradiated with microwaves [1]. This included microwaveinduced resistance oscillations (MIROs) [2] and a zeroresistance state (ZRS) [3]. Many microscopic mechanisms of MIRO have been proposed, mainly originating from the scattering-assisted electron transitions between different Landau levels in the presence of microwave excitation. The most developed theories account for spatial displacement of electrons along the applied dc field under scattering-assisted microwave absorption ("displacement" mechanism) [4,5], and an oscillatory contribution to the isotropic part of the electron distribution function ("inelastic" mechanism) [6]. Both these mechanisms describe the periodicity and phase of MIROs observed in experiments and can lead to an absolute negative conductivity σ < 0. ZRS emerges from the instability of a homogeneous state with σ < 0 and the nonequilibrium phase transition into a domain state with zero net resistance [22]. Two more alternative approaches to the MW-induced effects in dissipative resistance, such as the radiation-driven electron-orbit [8] and near-contact region [9] models, have been recently proposed.A striking similarity has been emphasized between QHE and ZRS: both effects exhibit vanishing longitudinal resistance R xx , when the propagation along the sample edge is ballistic, although the magnetic field intensity is quite different. One naturally expects that a strong magnetic field stabilizes edge states, and, therefore, that the QHE is robust against disorder [10]. It has been shown that microwave radiation can also stabilize guiding along sample edges in the presence of a relatively weak magnetic field leading to a ballistic dissipation-less transport regime, which also results in vanishing R xx [11]. Indeed such transport is much less robust than those in the QHE regime and requires samples with ultrahigh electron mobility. This model also avoids the fundamental assumption made in those approaches [4][5][6] that cyclotron harmonic absorption at high j can be explained by the presence of the short range potential, while in high mobility samples the long range potential plays a dominant role.The method used for probing the property of the edge states is nonlocal electrical measurement. If a finite voltage is applied between a pair of the probes, a net current appears along the sample edge, which can be detected by another pair of voltage probes far away from the bulk current path.In this letter we present studies of the nonlocal resistance in narrow (NQ...

Analog of microwave-induced resistance oscillations induced in GaAs heterostructures by terahertz radiation

“…In extremely clean samples the minima of the MIRO develop into ZRS [3][4][5], which are explained [10] in terms of an instability of the system and formation of current domains, occurring when the conductivity becomes negative under MW irradiation (see also [8,11,12]). In spite of numerous experiments and significant advances in their theoretical understanding, there is still no commonly accepted microscopic description of the effect [13,14] and the ongoing MIRO investigations remain challenging [15][16][17][18][19][20][21]. Consequently, new materials have been studied [22][23][24][25] and new theoretical models have been put forward [26][27][28][29][30].…”

“…In spite of numerous experiments and significant advances in their theoretical understanding, there is still no commonly accepted microscopic description of the effect [13,14] and the ongoing MIRO investigations remain challenging [15][16][17][18][19][20][21]. Consequently, new materials have been studied [22][23][24][25] and new theoretical models have been put forward [26][27][28][29][30].…”

Microwave-dressed electron–impurity interaction in a two-dimensional electron gas system under intense microwave radiation fields and weak magnetic fields

“…In particular, transport under microwave (MW) radiation field in high mobility 2DEGs revealed many intriguing and unexpected phenomena, of which MW-radiation induced magnetoresistance oscillations (MIRO) [3][4][5][6] and associated zeroresistance states (ZRS) [7,8] are probably the most striking manifestation. Therefore, nonequilibrium transport phenomena such as MIRO, ZRS, HIRO (Hall field-induced resistance oscillations) [9] and ZdRS (Zero-differential resistance states) [10], to mention but a few, in high-purity 2DEGs subjected simultaneously to MW radi-E-mail addresses: wywang2014@sina.cn (W.Y.…”

Gapped boundary theory of the twisted gauge theory model of three-dimensional topological orders

“…Systems bearing intrinsic topological orders in two [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] and three [15,[17][18][19][20][21][22][23][24][25][26][27][28][29] spatial dimensions have received substantial attention recently because they not only have greatly expanded and deepened our understanding of phases of matter but also have practical applications, in particular certain 2-dimensional topologically ordered systems can support topological quantum computation [5,30]. Celebrated candidates of two-dimensional topological phases include chiral spin liquids [2,31], Z 2 spin liquids [32][33][34], Abelian quantum Hall states [35][36][37], and non-Abelian fractional quantum Hall states [38][39][40][41][42].…”