Marek Potemski

Publications (10)2.54 Total impact

• Article: Magneto-absorption spectra of hydrogen-like yellow exciton series in cuprous oxide: excitons in strong magnetic ?fields

  Sergey L. Artyukhin, Dmitry Fishman, Clément Faugeras, Marek Potemski, Alexandre Revcolevschi, Maxim Mostovoy, Paul H. M. van Loosdrecht
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  ABSTRACT: We study the absorption spectra of the yellow excitons in Cu$_2$O in high magnetic fields using polarization-resolved optical absorption measurements with a high frequency resolution. We show that the symmetry of the yellow exciton results in unusual selection rules for the optical absorption of polarized light and that the mixing of ortho- and para- excitons in magnetic field is important. Our calculation of the energies of the yellow exciton series in an arbitrary magnetic field gives an excellent fit to experimental data and allows us to understand the complex structure of excitonic levels and their magnetic field dependence, which resolves the old-standing disagreement between the results of optical absorption and cyclotron resonance measurements.
  07/2012;
• Source

  Available from: arxiv.org

  Article: Carrier dynamics in epitaxial graphene close to the Dirac point

  Stephan Winnerl, Milan Orlita, Paulina Plochocka, Piotr Kossacki, Marek Potemski, Torben Winzer, Ermin Malic, Andreas Knorr, Michael Sprinkle, Claire Berger, Walter A. de Heer, Harald Schneider, Manfred Helm
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  ABSTRACT: We study the carrier dynamics in epitaxially grown graphene in the range of photon energies from 10 - 250 meV. The experiments complemented by microscopic modeling reveal that the carrier relaxation is significantly slowed down as the photon energy is tuned to values below the optical phonon frequency, however, owing to the presence of hot carriers, optical phonon emission is still the predominant relaxation process. For photon energies about twice the value of the Fermi energy, a transition from pump-induced transmission to pump-induced absorption occurs due to the interplay of interband and intraband processes.
  05/2011;
• Source

  Available from: arxiv.org

  Article: Epitaxial graphene electronic structure and transport

  Walt A de Heer, Claire Berger, Xiaosong Wu, Mike Sprinkle, Yike Hu, Ming Ruan, Joseph A Stroscio, Phillip N First, Robert Haddon, Benjamin Piot, Clément Faugeras, Marek Potemski, Jeong-Sun Moon
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  ABSTRACT: Since its inception in 2001, the science and technology of epitaxial graphene on hexagonal silicon carbide has matured into a major international effort and is poised to become the first carbon electronics platform. A historical perspective is presented and the unique electronic properties of single and multilayered epitaxial graphenes on electronics grade silicon carbide are reviewed. Early results on transport and the field effect in Si-face grown graphene monolayers provided proof-of-principle demonstrations. Besides monolayer epitaxial graphene, attention is given to C-face grown multilayer graphene, which consists of electronically decoupled graphene sheets. Production, structure and electronic structure are reviewed. The electronic properties, interrogated using a wide variety of surface, electrical and optical probes, are discussed. An overview is given of recent developments of several device prototypes including resistance standards based on epitaxial graphene quantum Hall devices and new ultrahigh frequency analogue epitaxial graphene amplifiers.
  Journal of Physics D Applied Physics 09/2010; 43(37):374007. · 2.54 Impact Factor
• Source

  Available from: ArXiv

  Article: Effect of a magnetic field on the two-phonon Raman scattering in graphene

  Clément Faugeras, Piotr Kossacki, D. M. Basko, Mario Amado, Mike Sprinkle, Claire Berger, Walter A. de Heer, Marek Potemski
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  ABSTRACT: We have studied, both experimentally and theoretically, the change of the so-called $2D$ band of the Raman scattering spectrum of graphene (the two-phonon peak near 2700~cm$^{-1}$) in an external magnetic field applied perpendicular to the graphene crystal plane at liquid helium temperature. A shift to lower frequency and broadening of this band is observed as the magnetic field is increased from 0 to 33~T. At fields up to 5--10~T the changes are quadratic in the field while they become linear at higher magnetic fields. This effect is explained by the curving of the quasiclassical trajectories of the photo-excited electrons and holes in the magnetic field, which enables us (i)~to extract the electron inelastic scattering rate, and (ii)~to conclude that electronic scattering accounts for about half of the measured width of the $2D$~peak.
  04/2010;
• Source

  Available from: ArXiv

  Article: Approaching the Dirac point in high mobility multi-layer epitaxial graphene

  Milan Orlita, Clement Faugeras, Paulina Plochocka, Petr Neugebauer, Gerard Martinez, Duncan K. Maude, Anne-Laure Barra, Mike Sprinkle, Claire Berger, Walter A. de Heer, Marek Potemski
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  ABSTRACT: Multi-layer epitaxial graphene (MEG) is investigated using far infrared (FIR) transmission experiments in the different limits of low magnetic fields and high temperatures. The cyclotron-resonance like absorption is observed at low temperature in magnetic fields below 50 mT, allowing thus to probe the nearest vicinity of the Dirac point and to estimate the conductivity in nearly undoped graphene. The carrier mobility is found to exceed 250,000 cm$^2$/(V.s). In the limit of high temperatures, the well-defined Landau level (LL) quantization is observed up to room temperature at magnetic fields below 1 T, a phenomenon unique in solid state systems. A negligible increase in the width of the cyclotron resonance lines with increasing temperature indicates that no important scattering mechanism is thermally activated, supporting recent expectations of high room-temperature mobilities in graphene.
  09/2008;
• Source

  Available from: ArXiv

  Article: Epitaxial graphene

  Walt A. de Heer, Claire Berger, Xiaosong Wu, Phillip N. First, Edward H. Conrad, Xuebin Li, Tianbo Li, Michael Sprinkle, Joanna Hass, Marcin L. Sadowski, Marek Potemski, Gerard Martinez
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  ABSTRACT: Graphene multilayers are grown epitaxially on single crystal silicon carbide. This system is composed of several graphene layers of which the first layer is electron doped due to the built-in electric field and the other layers are essentially undoped. Unlike graphite the charge carriers show Dirac particle properties (i.e. an anomalous Berry's phase, weak anti-localization and square root field dependence of the Landau level energies). Epitaxial graphene shows quasi-ballistic transport and long coherence lengths; properties which may persists above cryogenic temperatures. Paradoxically, in contrast to exfoliated graphene, the quantum Hall effect is not observed in high mobility epitaxial graphene. It appears that the effect is suppressed due to absence of localized states in the bulk of the material.Epitaxial graphene can be patterned using standard lithography methods and characterized using a wide array of techniques. These favorable features indicate that interconnected room temperature ballistic devices may be feasible for low dissipation high-speed nanoelectronics.
  05/2007;
• Source

  Available from: Andreas D. Wieck

  Article: Magneto-optical probing of weak disorder in a two-dimensional hole gas

  Leszek Bryja, Arkadiusz Wojs, Jan Misiewicz, Marek Potemski, Dirk Reuter, Andreas Wieck
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  ABSTRACT: In two-beam magneto-photoluminescence spectra of a two-dimensional valence hole gas we identify the three-level energy spectrum of a free positive trion with a field-induced singlet-triplet transition. The recombination spectrum of acceptor-bound trions is also detected, including a cyclotron replica corresponding to the hole shake-up process. The emergence of a shake-up peak at low temperature is shown to be a sensitive probe of the presence of a small number of impurities inside the high-mobility quantum well, and its relative position is directly related to the hole cyclotron mass. Comment: 4 pages, 5 figures
  10/2006;
• Source

  Available from: ArXiv

  Article: Effect of free carriers and impurities on the density of states and optical spectra of two-dimensional magnetoexcitons

  Anna Gładysiewicz, Leszek Bryja, Arkadiusz Wójs, Marek Potemski
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  ABSTRACT: The density of states (DOS) and absorption spectrum of weakly doped, narrow quantum wells in high magnetic fields are calculated by realistic exact diagonalization. The systems containing an electron-hole pair with and without an additional second electron are compared. In the DOS, the exciton-electron interaction is shown to fill the gaps between Landau levels and to yield additional discrete peaks corresponding to bound trion states. In absorption, the interaction with the additional free electron causes no shift or renormalization of main excitonic peaks. However, it results in additional weaker peaks associated with bound trions in the lowest or higher Landau levels. The calculation is supplemented with experimental photoluminescence and photoluminescence-excitation studies of two-dimensional holes and electrons in high magnetic fields.
  Phys. Rev. B. 09/2006; 74(11).
• Chapter: Dirac Particles in Epitaxial Graphene Films Grown on SiC

  Claire Berger, Xiaosong Wu, Phillip N. First, Edward H. Conrad, Xuebin Li, Michael Sprinkle, Joanna Hass, François Varchon, Laurence Magaud, Marcin L. Sadowski, Marek Potemski, Gérard Martinez, Walt A. de Heer
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  ABSTRACT: We report on the transport and structural properties of graphene layers grown epitaxially on hexagonal SiC. Experimentally, the charge carriers in epitaxial graphene are found to be chiral and the band structure is clearly related to the Dirac cone. To lowest order, epitaxial graphene appears to consist of stacked graphene sheets; the first layer is highly charged with the others carrying much lower charge.
  01/1970: pages 145-157;
• Article: Quantum Hall skyrmions in a hole gas with a large spin gap

  Leszek Bryja, Arkadiusz Wójs, Marek Potemski
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  ABSTRACT: Photoluminescence excitation spectra of a two-dimensional valence hole gas with large spin gap and strong disorder are studied in high magnetic fields. The characteristic field dependence of polarized emission associated with transitions from the lowest hole Landau level (LL) is the signature of quantum Hall ferromagnetism and small skyrmions around the LL filling factor ν=1. This interpretation is supported by realistic numerical calculations of the skyrmion binding energy.
  Phys. Rev. B. 73(24).