  The electronic states and optical transitions of a ZnO quantum ring
containing few interacting electrons in an applied magnetic field are found to
be very different from those in a conventional semiconductor system, such as a
GaAs ring. The strong Zeeman and Coulomb interaction of the ZnO system, exert a
profound influence on the electron states and on the optical properties of the
ring. In particular, our results indicate that the Aharonov-Bohm (AB) effect in
a ZnO quantum ring strongly depends on the electron number. In fact, for two
electrons in the ZnO ring, the AB oscillations become aperiodic, while for
three electrons (interacting) the AB oscillations completely disappear.
Therefore, unlike in conventional quantum ring topology, here the AB effect
(and the resulting persistent current) can be controlled by varying the
electron number.

Mesoscale and Nanoscale Physics