Giant magnetoresistance oscillations induced by microwave radiation and a zero-resistance state in a 2D electron system with a moderate mobility

Abstract

The effect of a microwave field in the frequency range from 54 to 140 GHz on the magnetotransport in a GaAs quantum well with AlAs/GaAs superlattice barriers and with an electron mobility no higher than 10 6 cm 2 /Vs is investigated. In the given two-dimensional system under the effect of microwave radiation, giant resistance oscillations are observed with their positions in magnetic field being determined by the ratio of the radiation frequency to the cyclotron frequency. Earlier, such oscillations had only been observed in GaAs/AlGaAs heterostructures with much higher mobilities. When the samples under study are irradiated with a 140-GHz microwave field, the resistance corresponding to the main oscillation minimum, which occurs near the cyclotron resonance, appears to be close to zero. The results of the study suggest that a mobility value lower than 10 6 cm 2 /Vs does not prevent the formation of zero-resistance states in magnetic field in a two-dimensional system under the effect of microwave radiation. Current interest in studying the transport in twodimensional (2D) electron systems is related to the recent observation of resistance oscillations in magnetic field that arise in high-mobility GaAs/AlGaAs heterostructures under the effect of microwave radiation [1]. It was found that these oscillations are periodic in the inverse magnetic field (1/B) with a period determined by the ratio of the microwave radiation frequency to the cyclotron frequency. The photoresponse oscillations in magnetic field in a high-mobility 2D system (such oscillations were predicted more than 30 years ago [2]) fundamentally differed from the behavior of photoresponse in GaAs/AlGaAs heterostructures with lower mobilities [3]. The effect of microwave radiation on the magnetotransport in GaAs/AlGaAs heterostructures of moderate quality was found to manifest itself as a photoresistance peak caused by the heating of the 2D electron gas under the magnetoplasma resonance conditions [4]. Soon after the first experimental observation of the microwave radiation-induced resistance oscillations in magnetic field in high-mobility GaAs/AlGaAs heterostructures, it was shown that the minima of these oscillations may correspond to resistance values close to zero [5,6,7]. This unexpected experimental result initiated intensive theoretical studies of the aforementioned phenomenon [7,8,9,10,11,12,13,14,15,16]. However, despite the multitude of theoretical publications, the mechanisms responsible for the resistance oscillations under the effect of a microwave field in 2D systems with large filling factors remain open to discussion. The role of the mobility of charge carriers in the manifestation of microwaveinduced zero-resistance states arising in magnetic field in 2D systems also remains unclear. It is commonly believed that the mobility should exceed 3 × 10 6 cm 2 /Vs[17]. As for the experimental studies of the photoresponse to microwave radiation in 2D systems in classically strong magnetic fields, such studies, excluding a few of them [17,18,19,2...

Theory of microwave-induced zero-resistance states in two-dimensional electron systems

“…There have been no systematic study of the role of the contacts in the microwave experiments on the 2DEG, but if the contacts, due to some reasons, turned out to be "more ideal" in the discussed sense, the observation of MIZRS could become possible even in samples with a moderate mobility. This may explain the experiment 33 in which the giant magnetoresistance oscillations and zero-resistance states have been observed at µ 10 6 cm 2 /Vs. The "negative resistance" observations of Ref.…”

“…In samples with µ 10 6 cm 2 /Vs the MIROs have not been observed (for the only exception see Ref. 33 ). In such samples, instead, the photoresistance measurements demonstrate a completely different photoresponse 5 : a weak Lorenzian peak corresponding to the excitation of the 2D magnetoplasmon, Figure 1(a).…”

Nonlinear resistance of two-dimensional electrons in crossed electric and magnetic fields

“…In response to microwave radiation and dc bias, strongly nonlinear electron transport [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32] that gives rise to unusual electron states [33,34,35,36,37,38,39] has been reported in two-dimensional systems of highly mobile electrons in a 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 interaction play essential roles [40,41,42,43,44,45,46,47,48,…”

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.…”