S. A. Tarasenko

Ioffe Physical Technical Institute, Sankt-Peterburg, St.-Petersburg, Russia

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Publications (129)280.53 Total impact

  • L. E. Golub, S. A. Tarasenko
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    ABSTRACT: The valley degeneracy of electron states in graphene stimulates intensive research of valley-related optical and transport phenomena. While many proposals on how to manipulate valley states have been put forward, experimental access to the valley polarization in graphene is still a challenge. Here, we develop a theory of the second optical harmonic generation in graphene and show that this effect can be used to measure the degree and sign of the valley polarization. We show that, at the normal incidence of radiation, the second harmonic generation stems from imbalance of carrier populations in the valleys. The effect has a specific polarization dependence reflecting the trigonal symmetry of electron valley and is resonantly enhanced if the energy of incident photons is close to the Fermi energy.
    11/2014;
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    ABSTRACT: The high-frequency (ac) conductivity of a high quality modulation doped GeSi/Ge/GeSi single quantum well structure with hole density $p$=6$\times$10$^{11}$cm$^{-2}$ was measured by the surface acoustic wave (SAW) technique at frequencies of 30 and 85~MHz and magnetic fields $B$ of up to 18 T in the temperature range of 0.3 -- 5.8 K. The acoustic effects were also measured as a function of the tilt angle of the magnetic field with respect to the normal of the two-dimensional channel at $T$=0.3 K. It is shown, that at the minima of the conductivity oscillations, holes are localized on the Fermi level, and that there is a temperature domain in which the high-frequency conductivity in the bulk of the quantum well is of the activation nature. The analysis of the temperature dependence of the conductivity at odd filling factors enables us to determine the effective $g_z$ factor. It is shown that the in-plane component of the magnetic field leads to an increase of the cyclotron mass and to a reduction of the $g_z$ factor. We developed a microscopic theory of these effects for the heavy-hole states of the complex valence band in quantum wells which describes well the experimental findings.
    11/2014;
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    ABSTRACT: We describe the fine structure of Dirac states in HgTe/CdHgTe quantum wells of critical and close-to-critical thickness and demonstrate the formation of an anticrossing gap between the tips of the Dirac cones driven by interface inversion asymmetry. By combining symmetry analysis, atomistic calculations, and k-p theory with interface terms, we obtain a quantitative description of the energy spectrum and extract the interface mixing coefficient. The zero-magnetic-field splitting of Dirac cones can be experimentally revealed in studying magnetotransport phenomena, cyclotron resonance, Raman scattering, or THz radiation absorption.
    11/2014;
  • A. V. Poshakinskiy, S. A. Tarasenko
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    ABSTRACT: We study the orbital and spin dynamics of charge carriers induced by non-overlapping linearly polarized light pulses in semiconductor quantum wells (QWs). It is shown that such an optical excitation with coherent pulses leads to a spin orientation of photocarriers and an electric current. The effects are caused by the interference of optical transitions driven by individual pulses. The distribution of carriers in the spin and momentum spaces depends on the QW crystallographic orientation and can be efficiently controlled by the pulse polarizations, time delay and phase shift between the pulses, as well as an external magnetic field.
    JETP Letters 04/2014; 99(11). · 1.52 Impact Factor
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    ABSTRACT: Photoluminescence (PL) and highly circularly-polarized magneto-PL (up to 50% at 6 T) from two-step bandgap InAs/InGaAs/InAlAs quantum wells (QWs) are studied. Bright PL is observed up to room temperature, indicating a high quantum efficiency of the radiative recombination in these QW. The sign of the circular polarization indicates that it stems from the spin polarization of heavy holes caused by the Zeeman effect. Although in magnetic field the PL line are strongly circularly polarized, no energy shift between the counter-polarized PL lines was observed. The results suggest that the electron and the hole g-factor to be of the same sign and close magnitudes.
    Applied Physics Letters 01/2014; 104(10). · 3.52 Impact Factor
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    P. S. Alekseev, M. M. Glazov, S. A. Tarasenko
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    ABSTRACT: We study the tunneling of conduction electrons through a (110)-oriented single-barrier heterostructure grown from III-V semiconductor compounds. It is shown that, due to low spatial symmetry of such a barrier, the tunneling current through the barrier leads to an electron spin polarization. The inverse effect, generation of a direct tunneling current by spin polarized electrons, is also predicted. We develop the microscopic theory of the effects and show that the spin polarization emerges due to the combined action of the Dresselhaus spin-orbit coupling within the barrier and the Rashba spin-orbit coupling at the barrier interfaces.
    01/2014; 89(15).
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    ABSTRACT: We report on the observation of magnetic quantum ratchet effect in metal-oxide-semiconductor field-effect-transistors on silicon surface (Si-MOSFETs). We show that the excitation of an unbiased transistor by ac electric field of terahertz radiation at normal incidence leads to a direct electric current between the source and drain contacts if the transistor is subjected to an in-plane magnetic field. The current rises linearly with the magnetic field strength and quadratically with the ac electric field amplitude. It depends on the polarization state of the ac field and can be induced by both linearly and circularly polarized radiation. We present the quasi-classical and quantum theories of the observed effect and show that the current originates from the Lorentz force acting upon carriers in asymmetric inversion channels of the transistors.
    Journal of physics. Condensed matter : an Institute of Physics journal. 12/2013; 26(25).
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    ABSTRACT: We study the electron spin relaxation in both symmetric and asymmetric GaAs/AlGaAs quantum wells (QWs) grown on (110) substrates in an external magnetic field B applied along the QW normal. The spin polarization is induced by circularly polarized light and detected by time-resolved Kerr rotation technique. In the asymmetric structure, where a {\delta}-doped layer on one side of the QW produces the Rashba contribution to the conduction-band spin-orbit splitting, the lifetime of electron spins aligned along the growth axis exhibits an anomalous dependence on B in the range 0<B<0.5 T; this results from the interplay between the Dresselhaus and Rashba effective fields which are perpendicular to each other. For larger magnetic fields, the spin lifetime increases, which is the consequence of the cyclotron motion of the electrons and is also observed in (001)-grown quantum wells. The experimental results are in agreement with the calculation of the spin lifetimes in (110)- grown asymmetric quantum wells described by the point group Cs where the growth direction is not the principal axis of the spin-relaxation-rate tensor.
    New Journal of Physics 12/2013; 16(4). · 4.06 Impact Factor
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    ABSTRACT: We report on the observation of the cyclotron-resonance-assisted photon drag effect. Resonant photocurrent is detected in InSb/InAlSb quantum wells structures subjected to a static magnetic field and excited by terahertz radiation at oblique incidence. The developed theory based on Boltzmann's kinetic equation is in a good agreement with the experimental findings. We show that the resonant photocurrent originates from the transfer of photon momentum to free electrons drastically enhanced at cyclotron resonance.
    Physical Review B 12/2013; 89(11). · 3.66 Impact Factor
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    ABSTRACT: We study the optically induced spin polarization, spin dephasing and diffusion in several high-mobility two-dimensional electron systems, which are embedded in GaAs quantum wells grown on (110)-oriented substrates. The experimental techniques comprise a two-beam magneto-optical spectroscopy system and polarization-resolved photoluminescence. Under weak excitation conditions at liquid-helium temperatures, we observe spin lifetimes above 100 ns in one of our samples, which are reduced with increasing excitation density due to additional, hole-mediated, spin dephasing. The spin dynamic is strongly influenced by the carrier density and the ionization of remote donors, which can be controlled by temperature and above-barrier illumination. The absolute value of the average electron spin polarization in the samples is directly observable in the circular polarization of photoluminescence collected under circularly polarized excitation and reaches values of about 5 percent. Spin diffusion is studied by varying the distance between pump and probe beams in micro-spectroscopy experiments. We observe diffusion lengths above 100 $\mu$m and, at high excitation intensity, a nonmonotonic dependence of the spin polarization on the pump-probe distance.
    Physical Review B 10/2013; 89(7). · 3.66 Impact Factor
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    ABSTRACT: 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≈7.2×105 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.
    Physical review. B, Condensed matter 06/2013; 87(23). · 3.66 Impact Factor
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    A. V. Poshakinskiy, S. A. Tarasenko
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    ABSTRACT: We develop the microscopic theory of electron spin dephasing in (110)-grown quantum wells where the electron scattering time is comparable to or exceeds the period of spin precession in the effective magnetic field caused by spin-orbit coupling. Structures with homogeneous and fluctuating Rashba field, which triggers the dephasing of electron spins aligned along the growth direction, are analyzed. We show that the Dresselhaus field, which is always present in zinc-blende-type quantum wells, suppresses the spin dephasing enabling very long spin lifetime of conduction electrons. The dependence of the spin lifetime on the electron mobility is found to be nonmonotonic reaching the minimum in structures where the scattering time is comparable to the period of spin precession in the effective magnetic field.
    Physical review. B, Condensed matter 04/2013; 87(23). · 3.66 Impact Factor
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    ABSTRACT: A periodically driven system with spatial asymmetry can exhibit a directed motion facilitated by thermal or quantum fluctuations. This so-called ratchet effect has fascinating ramifications in engineering and natural sciences. Graphene is nominally a symmetric system. Driven by a periodic electric field, no directed electric current should flow. However, if the graphene has lost its spatial symmetry due to its substrate or adatoms, an electronic ratchet motion can arise. We report an experimental demonstration of such an electronic ratchet in graphene layers, proving the underlying spatial asymmetry. The orbital asymmetry of the Dirac fermions is induced by an in-plane magnetic field, whereas the periodic driving comes from terahertz radiation. The resulting magnetic quantum ratchet transforms the a.c. power into a d.c. current, extracting work from the out-of-equilibrium electrons driven by undirected periodic forces. The observation of ratchet transport in this purest possible two-dimensional system indicates that the orbital effects may appear and be substantial in other two-dimensional crystals such as boron nitride, molybdenum dichalcogenides and related heterostructures. The measurable orbital effects in the presence of an in-plane magnetic field provide strong evidence for the existence of structure inversion asymmetry in graphene.
    Nature Nanotechnology 01/2013; · 31.17 Impact Factor
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    ABSTRACT: We report on the observation of the giant spin-polarized photocurrent in HgTe/HgCdTe quantum well (QW) of critical thickness at which a Dirac spectrum emerges. 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 gating. The photocurent data, accompanied by measurements of radiation transmission as well as Shubnikov-de Haas and quantum Hall effects, give an evidence that the enhancement of the photocurrent is caused by cyclotron resonance in a Dirac fermion system. The developed theory shows that the current is spin polarized and originates from the spin dependent scattering of charge carriers heated by the radiation.
    01/2013;
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    ABSTRACT: We report on the observation of the giant photocurrent in HgTe/HgCdTe quantum wells (QW) of critical thickness at which a Dirac spectrum emerges1,2. Exciting QW of 6.6 nm width by terahertz (THz) radiation and sweeping the 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. We show that the photocurrent is caused by cyclotron resonance (CR) in a Dirac fermion system, which allows us to obtain the electron velocity ν ~ 7.2 105 m/s. We develop a microscopic theory of the effect and show that the inherent spin-dependent asymmetry of the Dirac fermion scattering in QWs causes the electric current to flow.
    Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), 2013 38th International Conference on; 01/2013
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    ABSTRACT: We study the reflection of polarized optical pulses from resonant photonic structures formed by periodic, Fibonacci, and gradient sequences of quantum wells. The form and polarization of the reflected pulse are shown to be determined by the structure design and optical length. In structures with periodic quantum well arrangement, the response to ultrashort pulse is an optical signal with a sharp rise followed by an exponential decay or Bessel beats depending on the structure length. The duration of reflected pulses non-monotonically depends on the number of quantum wells reaching the minimum for a certain structure length which corresponds to the transition from superradiant to photonic-crystalline regime. We also study the conversion of pulse polarization in the longitudinal external magnetic field which splits the exciton resonance. Comparing periodic, Fibonacci, and gradient structures we show that the latter are more efficient for the conversion from linear to circular polarization.
    Physical review. B, Condensed matter 08/2012; 86(20). · 3.66 Impact Factor
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    ABSTRACT: Spin splittings in quantum wells have attracted considerable attention over the past decade due to potential application of semiconductor spin properties to “spintronic devices.” Recent experimental results stimulate theoretical investigations of new physical situations like unconventional growth directions. Here we focus on electron spin properties in (110)-oriented quantum wells that are of particular interest because qualitative symmetry analysis shows that spin relaxation by the D’yakonov-Perel’ mechanism should be strongly suppressed in this geometry. We combine symmetry analysis, envelope function theory, and tight-binding calculation and obtain quantitative description of the in-plane wave vector, well width, and applied electric field dependence of the spin structure of electron subbands in (110) quantum wells.
    Physical review. B, Condensed matter 05/2012; 85(20). · 3.66 Impact Factor
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    ABSTRACT: We report on the study of spin-polarized electric currents in diluted magnetic semiconductor (DMS) quantum wells subjected to an in-plane external magnetic field and illuminated by microwave or terahertz radiation. The effect is studied in (Cd,Mn)Te/(Cd,Mg)Te quantum wells (QWs) and (In,Ga)As/InAlAs:Mn QWs belonging to the well known II-VI and III-V DMS material systems, as well as, in heterovalent AlSb/InAs/(Zn,Mn)Te QWs which represent a promising combination of II-VI and III-V semiconductors. Experimental data and developed theory demonstrate that the photocurrent originates from a spin-dependent scattering of free carriers by static defects or phonons in the Drude absorption of radiation and subsequent relaxation of carriers. We show that in DMS structures the efficiency of the current generation is drastically enhanced compared to non-magnetic semiconductors. The enhancement is caused by the exchange interaction of carrier spins with localized spins of magnetic ions resulting, on the one hand, in the giant Zeeman spin-splitting, and, on the other hand, in the spin-dependent carrier scattering by localized Mn2+ ions polarized by an external magnetic field.
    Physical review. B, Condensed matter 04/2012; 86(8). · 3.66 Impact Factor
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    ABSTRACT: We report on the observation of terahertz radiation induced photocurrents in single-layer graphene samples subjected to an in-plane magnetic field. The photosignal is observed for both, linearly and circularly polarized radiation. A remarkable effect is that the current inverts its sign not only by switching the magnetic field direction, but as well by changing the radiation helicity from left- to right-handedness. We demonstrate that the photocurrent stems from strong structure inversion asymmetry (SIA) of samples originating from the presence of substrate and/or adatoms on graphene. The analysis shows that the observed effect represents a new type of ratchet effects: magnetic field induced ratchets. A microscopic theory of the observed effect is developed being in a good qualitative agreement with the experiment. Furthermore, the experiments open a promising access to the investigation of SIA which is of particular interest for the understanding of graphene properties as well as applications.
    Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), 2012 37th International Conference on; 01/2012
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    ABSTRACT: We observe photocurrents induced in single-layer graphene samples by illumination of the graphene edges with circularly polarized terahertz radiation at normal incidence. The photocurrent flows along the sample edges and forms a vortex. Its winding direction reverses by switching the light helicity from left to right handed. We demonstrate that the photocurrent stems from the sample edges, which reduce the spatial symmetry and result in an asymmetric scattering of carriers driven by the radiation electric field. The developed theory based on Boltzmann's kinetic equation is in a good agreement with the experiment. We show that the edge photocurrents can be applied for determination of the conductivity type and the momentum scattering time of the charge carriers in the graphene edge vicinity.
    Physical Review Letters 12/2011; 107(27):276601. · 7.73 Impact Factor

Publication Stats

992 Citations
280.53 Total Impact Points

Institutions

  • 2001–2014
    • Ioffe Physical Technical Institute
      Sankt-Peterburg, St.-Petersburg, Russia
  • 2013
    • Imperial College London
      Londinium, England, United Kingdom
    • Chinese Academy of Sciences
      • Institute of Physics
      Peping, Beijing, China
  • 2002–2013
    • Universität Regensburg
      • Institute of Experimental and Applied Physics
      Ratisbon, Bavaria, Germany
  • 2001–2013
    • Russian Academy of Sciences
      • Ioffe Physical-Technical Institute
      Moskva, Moscow, Russia