Tunable Magnetic Interaction In Semiconductor Nanostructures

The controllable magnetic interaction in semiconductornanostructures has strong application in spintronics and quantuminformation processing. In this thesis, we studies the quantum sizeeffect of the spin-orbit coupled electron mediated magneticinteraction in quantum well, and the effect of the electron-electroninteraction on the magnetic interaction between the localized spinsin two diluted magnetic semiconductor quantum dots insemiconductors embedded in semiconductor.By taking into account the quantum confinement, we calculatedthe Ruderman-Kittel-Kasuya-Yosida (RKKY) magnetic interactionbetween two magnetic impurities mediated by electrons withRashba and Dresselhaus spin-orbit couplings in a quantum well.The RKKY magnetic interaction of the present system consists ofconventional RKKY magnetic coupling, anisotropic magneticcouplings and Dzyaloshinsky-Moriya magnetic interaction. The above magnetic interactions strongly depend not only on thespin-orbit coupling strength, but also on the confined width and theabsolute positions of two localized spins in the directionperpendicular to the plane of the layered structure due to thequantum size effect. It provides a potential way to control the RKKYmagnetic interaction and its components in the quantum well withRashba spin-orbit coupling by both the applied gate voltage and thenanostructure geometry.Using the Keldysh Green’s function method and taking intoaccount electron-electron interaction, we calculated the RKKYmagnetic interaction between the localized spins of two dilutedmagnetic semiconductor (DMS) quantum dots embedded intwo-dimensional semiconductors. The electron-electron interactionis treated by using self-consistent mean field approximation. It wasshown that the RKKY interaction is strongly dependent on thediscrete energy levels in DMS quantum dots and their energy levelsplitting due to electron-electron interaction. Since the carrierenergy levels in DMS quantum dots may be adjusted by the appliedvoltage gates, the RKKY interaction of the present system isgate-controllable. It provides an alternate way to get thecontrollable RKKY magnetic interaction in semiconductornanostructures for potential application in quantum information processing.