Bauzha O. The role of spin - orbital and electron-electron interaction at formation of magnetic properties of quantum dots and rings.

The dissertation is devoted to theoretical study of the effect of spin-orbit and electron-electron interactions on the electron magnetization and magnetic susceptibility of small semiconductor quantum dots and rings. Characteristics of electron magnetization demonstrate a quite interesting behavior in the low-temperature range. The abrupt changes of magnetization at zero magnetic field value are attributed to the alternative crossing of the spin-split electron levels in the energy spectrum, caused by the spin-orbit interaction (an analog of the general Paschen-Back effect). This effect may be controlled by the external electric field or the dot (ring) design. The Kohn-Sham spin-density-functional theory was used to study the electronic states and magnetic properties of a two-dimensional parabolic quantum dot (quantum ring) with N=2-6 electrons. The influence of the bulk inversion asymmetry (the Dresselhaus term) and the system inversion asymmetry (the Rashba term) on the spin splitting of the electron energy states and electron magnetization are studied. The calculations performed for of InAs and InSb semiconductor quantum dots (quantum rings) demonstrate an enhancement of paramagnetism of the dots (rings). Key words: quantum dots, quantum rings, spin-orbit interaction, electron-electron interaction, magnetization.