The electronic and optical properties of magnetic quantum dots

Advances in lithographic technology have made it possible to fabricate systems in which electrons are confined magnetically. With an inhomogeneous circularly symmetric magnetic field, Bz, that was modulated so as the magnetic field was zero in the centre, electrons could, theoretically, be confined to a disk region. These systems are referred to as magnetic quantum dots, and the purpose of this thesis is to investigate their properties.;The eigenstates of the single electron system are calculated using new methods based on wave function matching. These enable the eigenstates to be determined for all values of Bz. Exact numerical diagonalisation is used to calculate the N-electron eigenstates, and new procedures are derived to evaluate the Coulomb matrix elements. It is shown that a dot is able to confide interacting electrons, and is therefore stable. Numerical results for GaAs and InSb dots indicate the existence of a stability boundary as a function of the dot radius and Bz. The form of this boundary is investigated and an analytic expression for it is obtained. The stability of the system is enhanced in a homogeneous external magnetic field, Bext. Results are also presented for the electron density, the pair distribution, and the pair correlation function.;The response of GaAs and InSb dots to far infrared radiation (FIR) is investigated as a function of Bz and Bext. The FIR response of the one and two electron systems are dissimilar, and this is shown to be a consequence of the interaction. Results for an InSb system with two electrons show a large splitting of the spectrum. This is investigated and an explanation is given. As a function of Bext, the single electron FIR response is similar to that of an electrostatic quantum dot in a magnetic field. The FIR spectrum of the equivalent two electron system is shown to have a rich structure, which should be experimentally verifiable.