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

Abstract

We report the experimental results from a dark study and a photo-excited study of the high mobility GaAs/AlGaAs system at large filling factors, ν. At large-ν, the dark study indicates several distinct phase relations ("Type-1", "Type-2", and "Type-3") between the oscillatory diagonal-and Hall-resistances, as the canonical Integral Quantum Hall Effect (IQHE) is manifested in the "Type-1" case of approximately orthogonal diagonal-and Hall resistance-oscillations. Surprisingly, the investigation indicates quantum Hall plateaus also in the "Type-3" case characterized by approximately "anti-phase" Hall-and diagonal-resistance oscillations, suggesting a new class of IQHE.Transport studies under microwave photo-excitation exhibit radiation-induced magneto-resistance oscillations in both the diagonal, Rxx, and off-diagonal, Rxy, resistances. Further, when the radiation-induced magneto-resistance oscillations extend into the quantum Hall regime, there occurs a radiation-induced non-monotonic variation in the amplitude of Shubnikov-de Haas (SdH) oscillations in Rxx vs. B, and a non-monotonic variation in the width of the quantum Hall plateaus in Rxy. The latter effect leads into the vanishing of IQHE at the minima of the radiation-induced Rxx oscillations with increased photo-excitation. We reason that the mechanism which is responsible for producing the non-monotonic variation in the amplitude of SdH oscillations in Rxx under photoexcitation is also responsible for eliminating, under photo-excitation, the novel "Type-3" IQHE in the high mobility specimen. INTRODUCTIONA 2-dimensional electron system (2DES) at high magnetic fields, B, and low temperatures, T , exhibits the integral quantum Hall effect (IQHE), which is characterized by plateaus in the Hall resistance R xy vs. B, at R xy = h/ie 2 , with i = 1,2,3,... and concurrent vanishing diagonal resistance R xx as T → 0 K, in the vicinity of integral filling factors of Landau levels, i.e., ν ≈ i. [1,2,3] With the increase of the electron mobility, µ, at a given electron density, n, and low T , IQHE plateaus typically become narrower as fractional quantum Hall effects (FQHE) appear in the vicinity of, where p/q denotes mostly odd-denominator rational fractions. [2,3] Experimental studies of the highest mobility specimens have typically focused upon FQHE and other novel phases. [2,3,4,5] Meanwhile, the possibility of new variations of IQHE that might appear with the canonical effect in the reduceddisorder specimen, especially at large-ν, has been largely unanticipated. In the first dark-study part of this paper, we show that three distinct phase relationships can occur between the oscillatory diagonal-and Hall-resistances in the high-mobility dark specimen at ν > 5, and that IQHE can be manifested in two of these variations. 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 sta...

Nearly massless Dirac fermions and strong Zeeman splitting in the nodal-line semimetal ZrSiS probed by de Haas–van Alphen quantum oscillations

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Terahertz photovoltaic detection of cyclotron resonance in the regime of radiation-induced magnetoresistance oscillations

“…Tung et al examined long Hall bars and Corbino rings at sub-millimeter wave frequencies, and reported a double lock-in photo-resistance signal up to 495 GHz. 23 Other experimental work by Mani et al 1,17,21,22 also indicated zero-resistance states and radiation-induced magneto-resistance oscillations in R xx above 100GHz.…”

“…Note that at these relatively large f , these radiation-induced oscillations do overlap the morerapidly-varying-with-B Shubnikov-de Haas (SdH) oscillations, see also ref. 17,21,22 . A close comparison of Fig.…”

“…Works examining this regime include refs. 1,15,[17][18][19][21][22][23] Here, ref. 15 exhibited radiation-induced magnetoresistance oscillations to 254 GHz.…”

Evolution of the linear-polarization-angle-dependence of the radiation-induced magnetoresistance-oscillations with microwave power

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