Observation of microwave induced resistance and photovoltage oscillations in MgZnO/ZnO heterostructures

Kärcher, Daniel; Shchepetilnikov, A. V.; Nefyodov, Y.-U. A.; Falson, Joseph; Дмитриев, И. А.; Kozuka, Y.; Maryenko, D.; Tsukazaki, Atsushi; Дорожкин, С. И.; Кукушкин, И. В.; Kawasaki, Masashi; Smet, J. H.

doi:10.1103/physrevb.93.041410

Cited by 34 publications

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References 41 publications

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“…As a result, the relative importance of these contributions depends on many parameters and their unequivocal disentanglement is a challenging experimental feat that remains to be accomplished [20]. Moreover, the inelastic contribution can completely mask the displacement contribution in high-density and low-mobility 2DESs, such as the MgZnO/ZnO samples used in a recent MIRO study [13], making it virtually impossible to extract correlation properties of the disorder potential from microwave photoresistance.Another prominent non-equilibrium phenomenon, HIRO, emerges when a sufficiently strong direct current I is sent through a 2DES placed in a varying B-field [4][5][6]. HIRO appear as 1/B-periodic oscillations in the differential resistance r and originate solely from the displacement contribution from the electron backscattering off short-range ("sharp") disorder [8,21].…”

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Hall field-induced resistance oscillations in MgZnO/ZnO heterostructures

et al. 2017

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We report on nonlinear magnetotransport in a two-dimensional electron gas hosted in a MgZnO/ZnO heterostructure. Upon application of a direct current, we observe pronounced Hall field-induced resistance oscillations (HIRO) which are well known from experiments on high-mobility GaAs/AlGaAs quantum wells. The unique sensitivity of HIRO to the short-range component of the disorder potential allows us to unambiguously establish that the mobility of our MgZnO/ZnO heterostructure is limited by impurities residing within or near the 2D channel. Demonstration that HIRO can be realized in a system with a much lower mobility, much higher density, and much larger effective mass than in previously studied systems, highlights remarkable universality of the phenomenon and its great promise to be used in studies of a wide variety of emerging 2D materials.Assessing the nature and magnitude of the disorder present in high-quality two-dimensional electron systems (2DESs) presents a challenging yet necessary experimental task. When cooled to a low temperature T and exposed to a magnetic field B, these systems are widely known to divulge a rich array of quantum phenomena which display both quantitative and qualitative dependencies on the underlying disorder. Unfortunately, standard magnetotransport measurements in isolation give limited insight into this disorder as not all carrier scattering events are reflected equally or separably in the measured resistance [1]. However, a better glimpse of key characteristics of the disorder potential may often be gained from non-equilibrium transport phenomena, such as microwave-induced resistance oscillations (MIRO) [2,3] and Hall field-induced resistance oscillations (HIRO) [4][5][6]. Both phenomena exploit the commensurability of the energy spacing between the centers of disorder-broadened Landau levels and either the photon energy of the incident radiation (MIRO) or the Hall voltage drop across the cyclotron orbit under applied direct current (HIRO). Importantly, the amplitudes of these oscillations and their B-dependencies contain information on specific scattering types [7][8][9][10].MIRO, appearing when a 2DES is exposed to microwave radiation of frequency ω = 2πf and a weak B-field, are controlled by ω/ω c , where ω c = eB/m ⋆ is the cyclotron frequency of an electron with the effective mass m ⋆ . [7,19] contributions. The former originates from the radiation-induced modification of scattering off impurities and carries important information about correlation properties of the disorder potential. The latter accounts for the radiation-induced changes to the distribution function and is controlled by the ratio of the transport and electron-electron scattering rates. As a result, the relative importance of these contributions depends on many parameters and their unequivocal disentanglement is a challenging experimental feat that remains to be accomplished [20]. Moreover, the inelastic contribution can completely mask the displacement contribution in high-density and low-mobility 2DESs, s...

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Hall field-induced resistance oscillations in MgZnO/ZnO heterostructures

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“…Apart from the extremely rich quantum Hall physics in strong magnetic fields [9,10], high-mobility 2DES display many prominent transport phenomena in low fields. Two salient examples of such phenomena are microwave-(MIRO) [11][12][13][14][15][16] and Hall field-induced resistance oscillations (HIRO) [17][18][19][20][21][22][23][24][25][26] which emerge when a 2DES is driven by microwave radiation and direct current, respectively.HIRO emerge due to elastic electron transitions between Landau levels, tilted by the Hall field, as a result of backscattering off short-range impurities [17,27,28]. The probability of these transitions is maximized each time the Hall voltage drop across the cyclotron diameter matches an integer multiple of the cyclotron energy.…”

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Hall field-induced resistance oscillations in a tunable-density GaAs quantum well

et al. 2017

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We report on Hall field-induced resistance oscillations (HIRO) in a 60 nm-wide GaAs/AlGaAs quantum well with an in situ grown back gate, which allows tuning the carrier density n. At low n, when all electrons are confined to the lowest subband (SB1), the HIRO frequency, proportional to the product of the cyclotron diameter and the Hall field, scales with n −1/2 , as expected. Remarkably, population of the second subband (SB2) significantly enhances HIRO, while their frequency now scales as n −1 . We demonstrate that in this two-subband regime HIRO still originate solely from backscattering of SB1 electrons. The unusual density dependence occurs because the population of SB2 steadily increases, while that of SB1 remains essentially unchanged. The enhancement of HIRO manifests an unexpected, step-like increase of the quantum lifetime of SB1 electrons, which reaches a record value of 52 ps in the two-subband regime.Continuous developments [1][2][3][4][5][6][7][8] in the molecular beam epitaxy and heterostructure design of 2D electron systems (2DES) have led to discoveries of a plethora of novel phenomena, especially in the field of low-temperature magnetotransport. Apart from the extremely rich quantum Hall physics in strong magnetic fields [9,10], high-mobility 2DES display many prominent transport phenomena in low fields. Two salient examples of such phenomena are microwave-(MIRO) [11][12][13][14][15][16] and Hall field-induced resistance oscillations (HIRO) [17][18][19][20][21][22][23][24][25][26] which emerge when a 2DES is driven by microwave radiation and direct current, respectively.HIRO emerge due to elastic electron transitions between Landau levels, tilted by the Hall field, as a result of backscattering off short-range impurities [17,27,28]. The probability of these transitions is maximized each time the Hall voltage drop across the cyclotron diameter matches an integer multiple of the cyclotron energy. As a result, the differential resistivity acquires a 1/B-periodic correction δr which can be described by [27] where ρ 0 = m ⋆ /e 2 nτ is the resistivity at zero magnetic field B, m ⋆ ≈ 0.07m 0 is the effective mass, n is the electron density, λ = exp(−π/ω c τ q ) is the Dingle factor, ω c = eB/m ⋆ is the cyclotron frequency, and τ, τ π , τ q are transport, backscattering, and quantum lifetimes, respectively [29]. The HIRO frequency (inverse period) B 1 is given bywhere E = Bj/ne is the Hall field and R c = √ 2πn/eB is the cyclotron radius.It is well known that in systems with several populated subbands, MIRO and HIRO often mix with magnetointersubband oscillations (MISO) [30][31][32][33][34][35][36]. However, it is also important to examine how MIRO and HIRO are affected by the population of the second subband in the absence of such mixing. For example, capacitance measurements in a wide quantum well provided direct evidence of microwave-induced non-equilibrium redistribution of electrons between two subbands but no significant change in MIRO upon second subband population [37]. However, unlike MIRO, who...

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“…Consequently, new materials have been studied [22][23][24][25] and new theoretical models have been put forward [26][27][28][29][30]. To the most pressing issues which need to be clarified experimentally and which might help to differentiate between the different models belong the MIRO polarization dependence [7,8,31] and the "bulk" or "edge" nature of the effect.…”

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

et al. 2016

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We report on the study of terahertz radiation-induced MIRO-like oscillations of magnetoresistivity in GaAs heterostructures. Our experiments provide an answer on two most intriguing questions-effect of radiation helicity and the role of the edges-yielding crucial information for an understanding of the MIRO (microwave-induced resistance oscillations) origin. Moreover, we demonstrate that the range of materials exhibiting radiation-induced magneto-oscillations can be largely extended by using high-frequency radiation. DOI: 10.1103/PhysRevB.94.081301 One of the most interesting phenomena recently observed in two-dimensional electron systems (2DES) is microwave (MW) -induced resistance oscillations (MIRO) and associated zero resistance states (ZRS) [1][2][3][4][5][6][7], reviewed, e.g., in [8]. Like Shubnikov-de Haas oscillations (SdH), MIRO are periodic on a 1/B scale, but occur at lower magnetic fields and show much weaker temperature dependence. Phenomenologically, they are very similar to Weiss oscillations [9], which reflect the commensurability between the cyclotron orbit radius and the period of a periodic potential. MIRO by contrast, reflect the commensurability between the MW photon energy 2π f and the cyclotron energy ω c . 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]. To the most pressing issues which need to be clarified experimentally and which might help to differentiate between the different models belong the MIRO polarization dependence [7,8,31] and the "bulk" or "edge" nature of the effect.So far the majority of experimental work has been done in the MW regime (1-350 GHz) and there are only a few reports on MIRO excited at terahertz (THz) frequencies [32][33][34]. Here we report on the observation of pronounced MIRO-like oscillations induced by THz radiation. We exploit the specific advantages of THz laser radiation not present in the MW regime, i.e., the possibility to focus it onto a spot smaller than the sample's size and easy control of the radiation's polarization. The most important features clearly detected on a large variety of samples are (i) a very weak dependence of the oscillations' amplitude on the photon helicity and (ii) the bulk nature of the effect. Furthermore, our study shows that the MIRO oscillations can be excited at THz frequencies even in the samples with low mobility, whereas in the MW range ultrahigh mobility samples are crucially needed for this type of experimen...

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Observation of microwave induced resistance and photovoltage oscillations in MgZnO/ZnO heterostructures

Cited by 34 publications

References 41 publications

Hall field-induced resistance oscillations in MgZnO/ZnO heterostructures

Hall field-induced resistance oscillations in MgZnO/ZnO heterostructures

Hall field-induced resistance oscillations in a tunable-density GaAs quantum well

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

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