Victor Sapega

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Scientific interests

He is mainly concerned with optical spectroscopy of bulk magnetic and nonmagnetic semiconductors and low-dimensional semiconductor structures like quantum wells, quantum dots and superlattices. His interest is focused on exciton/electron-phonon interaction, exchange interaction and spin related phenomena. Experimental methods used at present are Raman, spin flip-Raman scattering off and in resonance, photoluminescence of hot carriers, optical measurements in high magnetic and electric fields. Topics of his recent activities are spin related phenomena in quantum wells, quantum dots and ferromagnetic semiconductor GaMnAs.

Relevant Publications
  1. V.F. Sapega, M. Cardona, K. Ploog, E.L. Ivchenko, D.N. Mirlin, “Spin-flip Raman scattering in GaAs/AlGaAs multiple quantum wells”, Phys.Rev.B, 45, 4320 (1992).
  2. T. Ruf, V.I. Belitsky, J. Spitzer, V.F. Sapega, M. Cardona, K. Ploog, “Raman scattering from folded phonon dispersion gaps”, Phys. Rev. Lett. 71, 3035 (1993).
  3. V. F. Sapega, T. Ruf, M. Cardona, H.T. Grahn and K. Ploog, “Acoustic-phonon Raman scattering from Wannier-Stark levels in GaAs/AlAs superlattices”, Phys. Rev. B, 56, 1041 (1997).
  4. V.F. Sapega, T. Ruf, M. Cardona, “Spin-flip Raman study of exchange interactions in bulk GaAs:Mn”, Physica Status Solidi B, 226, 339 (2001).
  5. S. Dhar, O. Brandt, V.F. Sapega, M. Ramsteiner, K.H. Ploog, “Colossal magnetic moment of Gd in GaN”, Phys. Rev. Lett., 94, 037205, (2005).
  6. V.F. Sapega, M. Moreno, M. Ramsteiner, L. Daweritz, K.H. Ploog, “Polarization of valence band holes in the (Ga,Mn)As diluted magnetic semiconductor”, Phys. Rev. Lett., 94, 137401, (2005).
  7. V.F. Sapega, M. Ramsteiner , O. Brandt, L. Daweritz, K.H. Ploog, “Hot-electron photoluminescence study of the (Ga,Mn)As diluted magnetic semiconductor”, Phys. Rev. B, 73, 235208, (2006) .
  8. V.F. Sapega, O. Brandt, M. Ramsteiner, R.H. Ploog, “Hole spin polarization in GaAs : Mn/AlAs multiple quantum wells”, Phys. Rev. B, 75, 113310 (2007).
  9. V.F. Sapega, A.Trampert, R.H. Ploog, “Carrier Spin Polarization in Digital Mn/GaAs Ferromagnetic Structures Studied With Hot Electron Photoluminescence”, Phys. Rev. B, 77, 245301, (2008).
  10. V.F. Sapega, “Optical momentum alignment and spin orientation of hot electrons in GaAs/AlAs”, Superlattices Semicond. Sci. Technol. 23, 114016 (2008).
  11. V.F. Sapega, N.I. Sablina, I.E. Panaiotti, N.S. Averkiev, K.H. Ploog, “Hole spin polarization in the exchange field of the dilute magnetic (Ga,Mn)As semiconductor studied by means of polarized hot-electron photoluminescence spectroscopy”, Phys. Rev. B 80, 041202( R ) (2009).
  12. D.M. Wang, Y.H. Ren, P.W. Jacobs, S. Fahy, X. Liu, J.K. Furdyna, V.F. Sapega, R. Merlin, “Observation of Insulating Nanoislands in Ferromagnetic GaMnAs”, Phys. Rev. Lett. 102, 256401 (2009).
  13. A.V. Scherbakov, A.S. Salasyuk, A.V. Akimov, X. Liu, M. Bombeck, C. Brueggemann, D.R. Yakovlev, V.F. Sapega, J.K. Furdyna, M. Bayer, “Coherent Magnetization Precession in Ferromagnetic (Ga,Mn)As Induced by Picosecond Acoustic Pulses”, Phys. Rev. Lett. 105, 117204 (2010).
  14. I.A. Akimov, R.I. Dzhioev, V.L. Korenev, Yu.G. Kusrayev, V.F. Sapega, D.R. Yakovlev, and M. Bayer, “Optical Orientation of Mn2+ Ions in GaAs in Weak Longitudinal Magnetic Fields”, Phys. Rev. Lett. 106, 147402 (2011).