Geometrical Control of Spin Transitions in Quantum Rings

Abstract

We compute the energy difference between spin states in a quantum ring by employing the path integral Monte Carlo method. The focus is put on the effect of changes of the ring radius and the elliptical deformation on the spin of the ground state. The numerical results for three electrons reveal that the ground state can be tuned between a spin-unpolarized state and a spin-polarized state as the ring radius is modified. A circular ring with four electrons exhibits a Hund's rule ground state. With elliptical deformation the energy levels in the quantum ring hybridize which causes a spin depolarization of the ground state.