Spin-polarized electric currents in diluted magnetic semiconductor heterostructures induced by terahertz and microwave radiation

Olbrich, P.; Zoth, C.; Lutz, P.; Drexler, C.; Belkov, Vassilij; Terent'ev, Ya. V.; Tarasenko, S. A.; Семенов, А. Н.; Ivanov, S. V.; Yakovlev, D. R.; Wójtowicz, T.; Wurstbauer, Ursula; Schuh, Dieter; Ganichev, Sergey

doi:10.1103/physrevb.86.085310

Cited by 25 publications

(27 citation statements)

References 44 publications

(86 reference statements)

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“…The latter is a known fact for other III-V and II-VI heterostructures. [48][49][50][51] We consider the resonant absorption of THz radiation, which leads to the strong electron (hole) gas heating. The resulting steady-state nonequilibrium carrier distribution is formed by the energy gain due to the radiation absorption, electron-electron collisions thermalizing the electron gas, and the energy loss due to emission of phonons.…”

Section: Discussion and Microscopic Modelmentioning

confidence: 99%

Giant photocurrents in a Dirac fermion system at cyclotron resonance

et al. 2013

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We report on the observation of the giant photocurrents in HgTe/HgCdTe quantum well (QW) of critical thickness at which a Dirac spectrum emerges. At an exciting QW of 6.6 nm width by terahertz (THz) radiation and sweeping magnetic field we detected a resonant photocurrent. Remarkably, the position of the resonance can be tuned from negative (−0.4 T) to positive (up to 1.2 T) magnetic fields by means of optical doping. The photocurrent data, accompanied by measurements of radiation transmission as well as Shubnikov-de Haas and quantum Hall effects, prove that the photocurrent is caused by cyclotron resonance in a Dirac fermion system, which allows us to obtain the effective electron velocity v ≈ 7.2 × 10 5 m/s. We develop a microscopic theory of the effect and show that the inherent spin-dependent asymmetry of light-matter coupling in the system of Dirac fermions causes the electric current to flow.

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Section: Discussion and Microscopic Modelmentioning

confidence: 99%

Giant photocurrents in a Dirac fermion system at cyclotron resonance

et al. 2013

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“…The experiments were performed using a continuous wave (cw) methanol laser [50][51][52] emitting at the frequency f = 2.54 THz (wavelength of λ = 118 μm and photon energy ω = 10.5 meV). The radiation power P , being of the order of 50 mW at the sample surface, has been controlled by pyroelectric detectors and focused onto samples by a parabolic mirror.…”

Section: Samples and Methodsmentioning

confidence: 99%

Terahertz ratchet effects in graphene with a lateral superlattice

et al. 2016

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Experimental and theoretical studies on ratchet effects in graphene with a lateral superlattice excited by alternating electric fields of terahertz frequency range are presented. A lateral superlattice deposited on top of monolayer graphene is formed either by periodically repeated metal stripes having different widths and spacings or by interdigitated comblike dual-grating-gate (DGG) structures. We show that the ratchet photocurrent excited by terahertz radiation and sensitive to the radiation polarization state can be efficiently controlled by the back gate driving the system through the Dirac point as well as by the lateral asymmetry varied by applying unequal voltages to the DGG subgratings. The ratchet photocurrent includes the Seebeck thermoratchet effect as well as the effects of "linear" and "circular" ratchets, sensitive to the corresponding polarization of the driving electromagnetic force. The experimental data are analyzed for the electronic and plasmonic ratchets taking into account the calculated potential profile and the near field acting on carriers in graphene. We show that the photocurrent generation is based on a combined action of a spatially periodic in-plane potential and the spatially modulated light due to the near-field effects of the light diffraction.

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“…The effect of THz radiation on conductivity σ xx was studied in the temperature range from T = 2.5 K to about 20 K. The MIRO effect is most pronounced after the cooled samples have been exposed to room light, but the effect is also present for samples kept in the dark. All data presented in figures and tables were obtained after sample illumination.The THz experiments were performed using continuous wave (cw) CH 2 O 2 and CH 2 F 2 lasers [36][37][38] operating at frequencies f = 0.69 and 1.63 THz, respectively. The radiation at normal incidence is focused onto a spot size of about 3.4 mm diameter.…”

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confidence: 99%

“…The THz experiments were performed using continuous wave (cw) CH 2 O 2 and CH 2 F 2 lasers [36][37][38] operating at frequencies f = 0.69 and 1.63 THz, respectively. The radiation at normal incidence is focused onto a spot size of about 3.4 mm diameter.…”

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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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Spin-polarized electric currents in diluted magnetic semiconductor heterostructures induced by terahertz and microwave radiation

Cited by 25 publications

References 44 publications

Giant photocurrents in a Dirac fermion system at cyclotron resonance

Giant photocurrents in a Dirac fermion system at cyclotron resonance

Terahertz ratchet effects in graphene with a lateral superlattice

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

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