Energy structure and far-infrared spectroscopy of two electrons in a self-assembledquantum ring

Abstract

The energy levels and far-infrared absorption spectra of a self-assembled InAs ring with oneand two electrons in an external magnetic field are calculated numerically. We use a trulythree-dimensional effective mass model which considers finite potential barriers and massdependence on the energy and position, and includes strain effects. The resultsobtained indicate that far-infrared spectroscopy of self-assembled rings is verysensitive to electron–electron interactions. The exchange energy leads to aperiodicfractional Aharonov–Bohm oscillations of electronic states and rapid narrowing ofthe magnetic field windows corresponding to the spin singlet ground state. Ourresults also suggest that the symmetric form of parabolic confinement potential,which has been widely employed to describe quantum rings, is unsuitable forself-assembled rings as it poorly describes the relevant effects of the inner radius.