Classical ratchet effects in heterostructures with a lateral periodic potential

Olbrich, P.; Karch, J.; Ivchenko, E. L.; Kamann, Josef; März, Benjamin; Fehrenbacher, Markus; Weiss, Dieter; Ganichev, Sergey

doi:10.1103/physrevb.83.165320

Cited by 67 publications

(62 citation statements)

References 28 publications

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“…Microscopic theory developed in Ref. 25 shows that the helicity dependent photocurrent appears because the carriers in the laterally modulated quantum wells move in two directions and are subjected to the action of the two-component electric field. Symmetry analysis of the photocurrent shows that in our DDG structures described by C 1 point group symmetry, [47][48][49] it varies with radiation polarization after Eq.…”

Section: Discussionmentioning

confidence: 99%

“…It also has a large potential for the development of an all-electric detector of the radiation's polarization state, which was so far realized applying less sensitive photogalvanic effects only. [29][30][31][32] The observed phenomena is discussed in the framework of electronic ratchet 20,22,[24][25][26] and plasmonic ratchet effects excited in a 2D electron system with a spatially periodic dc in-plane potential. 9,22,27 …”

Section: Introductionmentioning

confidence: 99%

“…The first data obtained on dual-gated-structures demonstrated a substantial enhancement of the photoelectric response and an ability to control detector parameters by variation of individual gate bias voltage. 9 At the same time, THz electric field applied to FETs with asymmetric periodic dual gate structure is expected to give rise to electronic ratchet effects 20,[23][24][25][26] (for review, see Ref. 24) and plasmonic ratchet effects.…”

Section: Introductionmentioning

confidence: 99%

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Helicity sensitive terahertz radiation detection by dual-grating-gate high electron mobility transistors

Faltermeier

Olbrich

Probst

et al. 2015

Journal of Applied Physics

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Ultrahigh sensitive sub-terahertz detection by InP-based asymmetric dual-grating-gate high-electron-mobility transistors and their broadband characteristics Appl. Phys. Lett. 104, 251114 (2014) We report on the observation of a radiation helicity sensitive photocurrent excited by terahertz (THz) radiation in dual-grating-gate (DGG) InAlAs/InGaAs/InAlAs/InP high electron mobility transistors (HEMT). For a circular polarization, the current measured between source and drain contacts changes its sign with the inversion of the radiation helicity. For elliptically polarized radiation, the total current is described by superposition of the Stokes parameters with different weights. Moreover, by variation of gate voltages applied to individual gratings, the photocurrent can be defined either by the Stokes parameter defining the radiation helicity or those for linear polarization. We show that artificial non-centrosymmetric microperiodic structures with a twodimensional electron system excited by THz radiation exhibit a dc photocurrent caused by the combined action of a spatially periodic in-plane potential and spatially modulated light. The results provide a proof of principle for the application of DGG HEMT for all-electric detection of the radiation's polarization state. V C 2015 AIP Publishing LLC. [http://dx

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Helicity sensitive terahertz radiation detection by dual-grating-gate high electron mobility transistors

Faltermeier

Olbrich

Probst

et al. 2015

Journal of Applied Physics

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“…The beam had an almost Gaussian profile which was measured by a pyroelectric camera 30,31 . Right-and left-handed circularly polarized radiation were achieved by transmitting the linearly polarized laser beam through λ/4 crystal quartz plates [32][33][34] . The photoconductive response for normally incident radiation was measured as a function of magnetic field B up to 7 T applied perpendicularly to the QW plane.…”

Section: Samples and Experimental Techniquementioning

confidence: 99%

Magnetoresistance oscillations induced by high-intensity terahertz radiation

et al. 2017

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We report on observation of pronounced terahertz radiation-induced magneto-resistivity oscillations in AlGaAs/GaAs two-dimensional electron systems, the THz analog of the microwave induced resistivity oscillations (MIRO). Applying high power radiation of a pulsed molecular laser we demonstrate that MIRO, so far observed at low power only, are not destroyed even at very high intensities. Experiments with radiation intensity ranging over five orders of magnitude from 0.1 W/cm 2 to 10 4 W/cm 2 reveal high-power saturation of the MIRO amplitude, which is well described by an empirical fit function I/(1 + I/Is) β with β ∼ 1. The saturation intensity Is is of the order of tens of W/cm 2 and increases by six times by increasing the radiation frequency from 0.6 to 1.1 THz. The results are discussed in terms of microscopic mechanisms of MIRO and compared to nonlinear effects observed earlier at significantly lower excitation frequencies.Magnetotransport experiments in low-dimensional systems containing high mobility two-dimensional electron gases (2DEG) reveal many fundamental phenomena of quite different physical nature. The most prominent and well-known examples in linear dc transport are integer and fractional quantum Hall effects 1,2 in stronger magnetic field and Shubnikov -de Haas (SdH) 3,4 and Weiss 5oscillations at moderate fields. While linear transport phenomena in low-dimensional semiconductor systems have been systematically studied for several decades, in the last years terahertz/microwave-induced nonequilibrium transport in 2DEG is attracting an ever growing attention. In part, this is caused by the steadily expanding frequency range and rapid developments of terahertz science and technology [6][7][8][9][10][11] . Following the discovery of the microwave-induced resistance oscillations (MIRO) 12,13 and associated zero-resistance states 14-18 , the focus of recent research has largely shifted to nonequilibrium magnetotransport phenomena 19 . Similar to the SdH and Weiss oscillations, MIRO are 1/B-periodic oscillations and reflect the commensurability between the photon energy 2π f and the cyclotron energy ω c . Here, is the reduced Planck constant, f the microwave frequency and ω c the cyclotron frequency. Very recently, it was demonstrated that MIRO can be efficiently excited at substantially higher frequencies of several terahertz 20 . This work gave an experimental answer to two currently most intriguing questions regarding radiation helicity 18 and the role of the contacts/edges 21,22 . So far all studies of MIRO were performed at low radiation power smaller or of the order of a milliwatt19 . Here we demonstrate that MIRO are very robust and do not vanish even at very high power up to tens of kW/cm 2 . We have studied MIRO for frequencies between 0.6 and 1.1 THz and intensities varying by five orders of magnitude. We observe that high radiation intensity affects exclusively the amplitude of MIRO while both shape and phase of the oscillations are preserved. For all frequencies and all oscillation orde...

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“…The laser beam with power P ≈ 10 mW and an almost Gaussian profile, measured by a pyroelectric camera [21], is focused onto a spot of about 1.5 mm diameter. To create right-(σ + ) and left-handed (σ − ) polarized radiation λ/4 plates are used [22,23]. We study the photosignals by measuring the voltage drop U across a load resistance R L , see Fig.…”

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confidence: 99%

Photogalvanic probing of helical edge channels in two-dimensional HgTe topological insulators

et al. 2017

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We report on the observation of a circular photogalvanic current excited by terahertz laser radiation in helical edge channels of two-dimensional (2D) HgTe topological insulators (TIs). The direction of the photocurrent reverses by switching the radiation polarization from a right-handed to a left-handed one and, for fixed photon helicity, is opposite for the opposite edges. The photocurrent is detected in a wide range of gate voltages. With decreasing the Fermi level below the conduction band bottom, the current emerges, reaches a maximum, decreases, changes its sign close to the charge neutrality point (CNP), and again rises. Conductance measured over a ≈3 μm distance at CNP approaches 2e 2 /h, the value characteristic for ballistic transport in 2D TIs. The data reveal that the photocurrent is caused by photoionization of helical edge electrons to the conduction band. We discuss the microscopic model of this phenomenon and compare calculations with experimental data. DOI: 10.1103/PhysRevB.95.201103 The quantum spin Hall (QSH) effect occurs in 2D TIs and rests on the existence of conducting helical edge states while the bulk is insulating [1][2][3][4]. In contrast to the quantum Hall effect, the formation of these edge states requires no magnetic field: they stem from the band inversion caused by strong spin-orbit interaction and are topologically protected by time reversal symmetry. Given that the spin-up and spin-down electrons propagate along an edge in opposite directions, i.e., the spin projection is locked to the k vector, the edge channels are helical in nature. The first experimental evidence for the QSH effect was obtained in HgTe quantum wells (QWs) [5] by observing a resistance plateau around h/2e 2 in the longitudinal resistance of a mesoscopic Hall bar. Here h is Planck's constant and e is the electron charge. This observation was further confirmed by nonlocal experiments in the ballistic [6] and diffusive [7] transport regime. Conducting edge channels were later probed by scanning SQUID microscopy [8], scanning gate microscopy [9], microwave impedance microscopy [10], and by analyzing supercurrents [11]. The spin polarization of the edge states was investigated so far by electrical means only: by detecting the spin to charge conversion in devices utilizing the inverse spin Hall effect [12] or with ferromagnetic contacts [13].Here we use circularly polarized terahertz radiation to excite selectively spin-up and spin-down electrons circling clockwise and counterclockwise around a sample. We show that the excitation causes an imbalance in the electron distribution between positive and negative wave vectors. This is probed as the associated photogalvanic [14,15] current, which reverses its direction upon switching the helicity.The experiments have been carried out on Hg 0.3 Cd 0.7 Te/HgTe/Hg 0.3 Cd 0.7 Te single QW structures with a well width of 8 nm having inverted band ordering. We used this width to maximize the energy gap to about 25 meV [4,5]. Structures were grown by molecular beam epitaxy o...

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Classical ratchet effects in heterostructures with a lateral periodic potential

Cited by 67 publications

References 28 publications

Helicity sensitive terahertz radiation detection by dual-grating-gate high electron mobility transistors

Helicity sensitive terahertz radiation detection by dual-grating-gate high electron mobility transistors

Magnetoresistance oscillations induced by high-intensity terahertz radiation

Photogalvanic probing of helical edge channels in two-dimensional HgTe topological insulators

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