Magnetoexcitons in quantum-ring structures: a novel magnetic interference effect

Abstract

A novel magnetic interference effect is proposed for a neutral, but polarizable exciton in a quantum ring with a finite width. The magnetic interference effect originates from the nonzero dipole moment in the exciton. The ground state of exciton acquires a nonzero angular momentum with increasing normal magnetic field. This leads to the suppression of the photoluminescence in defined windows of the magnetic field.

Polarization and Aharonov-Bohm oscillations in quantum-ring magnetoexcitons

“…9,10,11,13 We should emphasize that these prior analysis are based on a non-interacting picture, with the oscillations arising from the different dispersions for electrons and holes. We show that such ground-state oscillations remain only for very weak interaction strengths.…”

“…The manifestation of the optical Aharonov-Bohm 1 (AB) effect in neutral and charged excitons in semiconductor quantum rings has received considerable attention in recent years from both theoretical 2,3,4,5,6,7,8,9,10,11,12,13 and experimental 14,15 groups. In contrast to the cumulative-phase ABE in electronic systems, 16,17 the optical ABE originates from the difference between the phases acquired by the electron and hole wave functions as the magnetic flux threads the ring.…”

“…However, an enhancement of this effect is expected when the exciton is radially polarized, either by the application of an external electric field 8 or due to a radial asymmetry in the effective confinement for electrons and holes. 9,10,11,13 In the latter case, differences in the valence and conduction band profiles lead to different effective ring radii for holes and electrons, and therefore distinct magnetic flux, giving rise to a field-dependent phase difference between the electron and hole wave functions. The resulting excitonic AB effect stems from the effective magnetic phase acquired by the wave function of an electron-hole pair as it goes around the ring.…”

Impurity effects on the Aharonov-Bohm optical signatures of neutral quantum-ring magnetoexcitons

“…This represents the selection rules on the electron emission. 10,11,12 If the exciton is on state |Ψ exct i , the emission intensity I i is then given by:…”

Excitons in quantum-ring structures in a magnetic field: optical properties and persistent currents

“…2b). For the magnetic moment of the exciton we obtain: LLL =+ becomes nonzero, the low-temperature PL intensity becomes strongly suppressed [9]. By comparing the limits of strong and weak…”