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Optical properties and quantum transitions with the participation of two–dimensional magnetoexcitons


Author: Podlesnîi Igor
Degree:doctor of physics and mathematics
Speciality: 01.04.02 - Theoretical and mathematical physics
Year:2010
Scientific adviser: Sveatoslav Moscalenco
doctor habilitat, professor, Institute of Applied Physics, Academy of Sciences of Moldova
Institution: Institute of Applied Physics, Academy of Sciences of Moldova
Scientific council: DH 02-01.04.02
Institute of Applied Physics, Academy of Sciences of Moldova

Status

The thesis was presented on the 11 December, 2009
Approved by NCAA on the 11 February, 2010

Abstract

Adobe PDF document1.63 Mb / in romanian
Adobe PDF document1.65 Mb / in english

Keywords

Two–dimensional magnetoexciton, Bose–Einstein condensation (BEC), energy spectrum, quantum transitions, cyclotron resonance, optical orientation.

Summary

The PhD thesis consists of introduction, three original chapters, conclusions, recommenda-tions and bibliography. The volume of the PhD thesis is 97 pages with 10 figures and 51 refe-rences. Basic results of the dissertation paper were published in the form of 44 scientific works (13 articles and 31 abstracts).

Field of investigation: Theoretical investigations in the condensed matter physics.

Objectives of the PhD thesis and scientific novelty of the obtained results.

The thesis is dedicated to the solution of two interdependent questions of the theory of two–dimensional excitons and electron–hole pairs in a high magnetic field.

First of them is the determination of more exact expressions for the wave function and en-ergy of the lowest exciton band. On this base the Bose–Einstein Condensation (BEC) on the su-perposition exciton state as well as on the excited Landau levels is investigated.

The second one is the explanation of the exciton–cyclotron resonance phenomenon in full accordance with the experimental data. To this end the electron–radiation interaction Hamilto-nian in the second quantization representation was deduced.

We have also proved that the probabilities of the quantum transitions and the absorption band shapes essentially depend on the light circular polarization giving rise to optical orientation phenomena such as electron spin polarization and exciton optical alignment.

Theoretical significance and practical value of the PhD thesis.

The work is devoted to the fundamental aspects of the physics of two–dimensional elec-tron–hole systems in nanostructures in the presence of a strong magnetic field. At the same time the work has the practical importance, since it explained the combined magnetoexciton–cyclotron resonance in full accordance with the experimental data. Some recommendations for the former experimental investigation are proposed.

Summary


1. ENERGY SPECTRUM OF TWO–DIMENSIONAL MAGNETOEXCITONS AND THEIR BOSE–EINSTEIN CONDENSATION ON THE SUPERPOSITION STATE
  • 1.1. Matrix elements of the Coulomb interaction of the electrons and holes [38]
  • 1.2. Wave functions and energy spectrum of four magnetoexciton bands [38]
  • 1.3. Bose–Einstein Condensation of two–dimensional magnetoexcitons on the superposition state as well as on the excited Landau levels
  • 1.4. Conclusions

2. ELECTRON–PHOTON INTERACTION IN TWO–DIMENSIONAL SYSTEMS IN HIGH PERPENDICULAR MAGNETIC FIELD.
  • 2.1. Hamiltonian of the electron–radiation interaction.
  • 2.2. Dipole active and quadrupole active quantum transitions
  • 2.3. Conclusions

3. COMBINED MAGNETOEXCITON–CYCLOTRON RESONANCE IN TWO–DIMENSIONAL STRUCTURES.
  • 3.1. Optical orientation, spin polarization and alignment of 2D magnetoexcitons in the presence of background electrons.
  • 3.2. The absorption band shapes in Faraday geometry and in two light circular polarizations.
  • 3.3. Conclusions