Vertically coupled double quantum rings at zero magnetic field

Abstract

Within local-spin-density functional theory, we have investigated the `dissociation' of few-electron circular vertical semiconductor double quantum ring artificial molecules at zero magnetic field as a function of inter-ring distance. In a first step, the molecules are constituted by two identical quantum rings. When the rings are quantum mechanically strongly coupled, the electronic states are substantially delocalized, and the addition energy spectra of the artificial molecule resemble those of a single quantum ring in the few-electron limit. When the rings are quantum mechanically weakly coupled, the electronic states in the molecule are substantially localized in one ring or the other, although the rings can be electrostatically coupled. The effect of a slight mismatch introduced in the molecules from nominally identical quantum wells, or from changes in the inner radius of the constituent rings, induces localization by offsetting the energy levels in the quantum rings. This plays a crucial role in the appearance of the addition spectra as a function of coupling strength particularly in the weak coupling limit.

18 pages, 8 figures, submitted to Physical Review B

References in corpus (4)

• Optical transitions in quantum ring complexes
• Molecular phases in coupled quantum dots
• Charge-localization and isospin-blockade in vertical double quantum dots
• Spin Effects in a Quantum Ring

Cited by in corpus (5)

• Control of the persistent currents in two interacting quantum rings through the Coulomb interaction and inter-ring tunneling
• Electron-acoustic-phonon scattering and electron relaxation in two-coupled quantum rings
• Characteristic molecular properties of one-electron double quantum rings under magnetic fields
• Artificial molecular quantum rings under magnetic field influence
• Isospin phases of vertically coupled double quantum rings under the influence of perpendicular magnetic fields