Observation of cyclotron resonance in the photoconductivity of two-dimensional electrons

Maan, J. C.; Englert, Th.; Tsui, D. C.; Gossard, A. C.

doi:10.1063/1.93197

Cited by 74 publications

(31 citation statements)

References 5 publications

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“…kind [15][16][17][18][19][20][21] was done in an ideal quantum Hall state and explained by the heating effect due to the nanosecond to microsecond terahertz pulses they employed. Therefore, the idea of light-induced IQHE has not been explored yet.…”

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confidence: 99%

Light-induced electron localization in a quantum Hall system

et al. 2017

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An insulating bulk state is a prerequisite for the protection of topological edge states 1 . In quantum Hall systems, the thermal excitation of delocalized electrons is the main route to breaking bulk insulation 2 . In equilibrium, the only way to achieve a clear bulk gap is to use a high-quality crystal under high magnetic field at low temperature. However, bulk conduction could also be suppressed in a system driven out of equilibrium such that localized states in the Landau levels are selectively occupied. Here we report a transient suppression of bulk conduction induced by terahertz wave excitation between the Landau levels in a GaAs quantum Hall system. Strikingly, the Hall resistivity almost reaches the quantized value at a temperature where the exact quantization is normally disrupted by thermal fluctuations. The electron localization is realized by the long-range potential fluctuations, which are a unique and inherent feature of quantum Hall systems. Our results demonstrate a new means of e ecting dynamical control of topology by manipulating bulk conduction using light.The integer quantum Hall effect (IQHE) is a universal phenomenon observable in two-dimensional electron systems under high magnetic field (B). The Hall resistivity (ρ xy ) is quantized and the longitudinal resistivity (ρ xx ) becomes zero irrespective of the detailed properties of the host materials [2][3][4][5][6][7] . This universality has lead to a new physical concept of topological invariant that defines the quantized value of ρ xy (ref. 8). In systems with sample boundaries, edge metallic states appear according to the bulk/edge correspondence 9 and carry quantized Hall current. The edge states are protected by the bulk gap between the Landau levels (LLs), which prohibits the scattering between macroscopically separated edge states 10,11 . In realistic situations, we need to take into account the impurity and finite-temperature effect. The LLs are broadened with delocalized states in the centre, sandwiched by localized states induced by Anderson localization 12,13 (Fig. 1d). At finite temperatures, the delocalized states are broadened and thermally populated, which makes the bulk conductive 2,14 . As a result, the scattering between edge states is allowed and ρ xy (ρ xx ) is no longer quantized (zero).In this paper, we demonstrate a transient suppression of bulk conduction and a recovery of the quantized ρ xy by selectively populating the localized electronic states. A direct way to manipulate the electron distribution in LLs is inter-LL transition by resonant light absorption (typically in the terahertz frequency region). To verify this strategy for realizing light-induced IQHE, we performed transient Hall measurements on a quantum Hall system with a non-equilibrium electron distribution induced by picosecond terahertz pulse excitation. Previous research of this kind [15][16][17][18][19][20][21] was done in an ideal quantum Hall state and explained by the heating effect due to the nanosecond to microsecond terahertz pulses they empl...

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confidence: 99%

Light-induced electron localization in a quantum Hall system

et al. 2017

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“…This is explained by the heating effect of the THz radiation (bolometric response, see e.g. [2,3,7]). At the cyclotron resonance (CR) position, where E p is equal to the cyclotron energyhw c =heB/m * (with the effective mass m * = 0.067 m e ), we see the following behavior: if the QH-plateau position is near to the CR-position the PR is massively enhanced (the case of overlapping of the bolometric and CR effect).…”

Section: Measurements On Gaas/algaas Heterostructuresmentioning

confidence: 99%

“…Although, the first investigations have been done more than 20 years ago, the mechanisms of the photoconductivity are not completely clear yet. Furthermore, the application of QH systems as high-performance THz detectors is discussed [2][3][4].…”

Section: Introductionmentioning

confidence: 99%

Terahertz photoconductivity in GaAs/AlGaAs and HgTe/HgCdTe quantum Hall devices

Stellmach

Bonk

Vasilyev

et al. 2006

Phys. Status Solidi (c)

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We present measurements of the THz photoconductivity on different quantum Hall systems. GaAs/AlGaAs and HgTe/HgCdTe (MCT) heterostructures with Hall-bar and Corbino geometry are investigated. A recipe for the preparation of metallic Corbino contacts on MCT is shown. The system is excited by the radiation of a p-Ge laser (tunable from 1.7 to 2.5 THz) and the photoresponse (PR) is measured versus the magnetic field B. We observe enhanced PR around integer filling factors (bolometric PR) and cyclotron resonance (CR) effects. Because of the lower effective mass in MCT, the CR in this system appears at a relatively low magnetic field (≈ 2 T). This is appropriate for possible applications. Finally we present time resolved measurements of the PR on the GaAs system. We find relaxation times from about 10 to over 200 ns, which depend on the geometry, the applied source-drain voltage and the on mobility of the sample.

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“…It follows that a long and narrow QHE device is expected to function as a sensitive narrow-band THz detector. In reality, the mechanism of photoresponse is somewhat more complicated, as has been a subject of a series of earlier experimental studies [11][12][13][14][15]. Simply described, the mechanism in the bulk region can be regarded as a bolometric effect as first suggested in [11], namely the excess energy gained by excited electrons and holes being transferred to the other cold electron below the Fermi sea via the electron-electron interaction, leading to a slight increase in the effective electron temperature, T eff , which in turn causes ρ x x to increase.…”

Section: Qhe Detectorsmentioning

confidence: 99%