Nichtlineare optische Spektroskopie zur Untersuchung der magnetischen Eigenschaften von Halbleitern
Final Report Abstract
Investigations performed in the frame of this project cover the following topics: I. Second harmonic generation in centrosymmetric magnetic semiconductors EuTe and EuSe; II. second harmonic generation spectroscopy of excitons in ZnO; III. magnetic- and electric-field-induced second harmonic generation in GaAs; IV. third harmonic generation spectroscopy of EuTe, EuSe and ZnO. We use the techniques of the second harmonic generation (SHG) and third harmonic generation (THG) spectroscopy of semiconductors, when the generated signal is measured in a wide spectral range with the focus to the states in vicinity of the semiconductor band gap, where the nonlinear optical response is enhanced by band-to-band optical transitions and by exciton resonances. For ZnO it allows us to develop SHG exciton spectroscopy to investigate various exciton states as well as their mixing under application of external magnetic fields. Microscopic theory for SHG at these exciton states has been developed and it is in a very good agreement with experimental appearances. Also the magneto-Stark effect suggested for excitons in 60th has been found as a leading mechanism for enhancing SHG signal from 2s/2p exciton states mixed in external magnetic field. SHG studies of EuTe and EuSe semiconductors demonstrate that even in centrosymmetric materials, where crystallographic SHG in symmetry forbidden, magnetization-induced SHG can be strong and allows to follow changes in magnetic phases with increasing magnetic field. Also microscopic mechanism of SHG has been suggested here accounting for specifics of the optical gap formed by internal transitions of Eu2+ ions. Joint action of the magnetic- and electric fields for SHG on excitons in GaAs has been studied. Spectroscopy of THG has been developed and approved for EuTe, EuSe and ZnO, being an informative complimentary technique to SHG.
Publications
- Spin-induced optical second harmonic generation in the centrosymmetric magnetic semiconductors EuTe and EuSe. Phys. Rev. Lett. 103, 057203 (2009)
B. Kaminski, M. Lafrentz, R. V. Pisarev, D. R. Yakovlev, V. V. Pavlov, V. A. Lukoshkin, A. B. Henriques, G. Springholz, G. Bauer, E. Abramof, P. H. O. Rappl, and M. Bayer
- Novel mechanisms of optical harmonics generation in semiconductors. Phys. Stat. Sol. (b) 247, 1498-1504 (2010)
R. V. Pisarev, B. Kaminski, M. Lafrentz, V. V. Pavlov, D. R.Yakovlev, and M. Bayer
- Optical second harmonic generation in the centrosymmetric magnetic semiconductors EuTe and EuSe. Phys. Rev. B 81, 155201 (1-15) (2010)
B. Kaminski, M. Lafrentz, R. V. Pisarev, D. R. Yakovlev, V. V. Pavlov, V. A. Lukoshkin, A. B. Henriques, G. Springholz, G. Bauer, E. Abramof, P. H. O. Rappl, and M. Bayer
- Optical third-harmonic spectroscopy of the magnetic semiconductor EuTe. Phys. Rev. B 82, 235206 (1-13) (2010)
M. Lafrentz, D. Brunne, B. Kaminski, V. V. Pavlov, A. B. Henriques, R. V. Pisarev, D. R. Yakovlev, G. Springholz, G. Bauer, E. Abramof, P. H. O. Rappl, and M. Bayer
- Optical third harmonic generation in the magnetic semiconductor EuSe. Phys. Rev. B 85, 035206 (1-6) (2012)
M. Lafrentz, D. Brunne, B. Kaminski, V. V. Pavlov, R. V. Pisarev, A. B. Henriques, D. R. Yakovlev, G. Springholz, G. Bauer, and M. Bayer
(See online at https://doi.org/10.1103/PhysRevB.85.035206) - Magneto-Stark Effect of Excitons as the Origin of Second Harmonic Generation in ZnO. Phys. Rev. Lett. 110, 116402 (2013)
M. Lafrentz, D. Brunne, B. Kaminski, V.V. Pavlov, A.V. Rodina, R.V. Pisarev, D. R. Yakovlev, A. Bakin, and M. Bayer
(See online at https://doi.org/10.1103/PhysRevLett.110.116402)
