Donor-bound electrons in quantum rings under magnetic fields

Abstract

We theoretically study donor-bound electron states in two-dimensional quantum rings of finite width. A strong magnetic field is applied perpendicular to the plane of the quantum ring. The resulting electronic states are obtained within the effective-mass approximation. For on-center donors, the radial Hamiltonian for the envelope function is exactly diagonalized, and the corresponding energy levels for different angular momenta are studied as a function of the applied magnetic field. Confinement properties change rapidly with the external magnetic field. An abrupt change of the localization properties appears at a critical magnetic field, since the electron is mainly localized around the impurity. This transition gives rise to well-defined anticrossing of levels as a function of the magnetic field. Intraband transitions are found to carry relevant information of these confining properties of the rings.