Effect of an electric field on the Bohm-Aharonov oscillations in the electronic spectrum of a quantum ring

We have studied the effects of an external electric field on the electronic and optical spectra of a semiconductor quantum ring threaded by a magnetic flux. The calculations were performed within a single-particle formalism using the effective-mass approximation. An electric field applied in the ring plane destroys the rotational invariance, mixing the states with different angular momentum and suppressing the oscillations of the ground-state energy as a function of the magnetic field. However, for excited states whose electronic wave function are allowed to spread out along the ring, periodic Bohm-Aharonov-type oscillations are found. The range of energies for which these oscillations occur can be controlled by changing the electric-field strength. To explore the possibility that this effect can be observed in future optical measurements we have calculated the absorption coefficient for different configurations of magnetic and electric fields. Our results show very rich spectra for quantum rings in the presence of electric fields, which effectively displays the signature of the Bohm-Aharonov effect.