Isospin phases of vertically coupled double quantum rings under the influence of perpendicular magnetic fields

Abstract

Vertically coupled double quantum rings submitted to a perpendicular magnetic field B are addressed within the local spin-density-functional theory. We describe the structure of quantum ring molecules containing up to 40 electrons considering different inter-ring distances and intensities of the applied magnetic field. When the rings are quantum mechanically strongly coupled, only bonding states are occupied and the addition spectrum of the artificial molecules resembles that of a single-quantum ring, with some small differences appearing as an effect of the magnetic field. Despite the latter's tendency to flatten the spectra, in the strong-coupling limit, some clear peaks are still found even when B 0 that can be interpretated from the single-particle energy levels similarly as in the zero magnetic field case, namely, in terms of closed-shell and Hund's-rule configurations. By increasing the inter-ring distance, the occupation of the first antibonding orbitals washes out such structures and the addition spectra become flatter and irregular. In the weak-coupling regime, numerous isospin oscillations are found as functions of B.

Linear and nonlinear optical absorption coefficients in GaAs/Ga1−xAlxAs concentric double quantum rings: Effects of hydrostatic pressure and aluminum concentration

“…Since the first quantum rings (QRs) of nanoscopic sizes were fabricated [8,9], these fascinating systems have drawn a considerable attention due to the interest in studying physical phenomena such as the Aharonov-Bohm effect [10][11][12][13] and the appearance of persistent currents [14]. Theoretical studies on vertically [15][16][17][18] and laterally [19,20] coupled double QRs have discussed the molecular properties of these systems. QRs may also be coupled concentrically.…”

Ground state and infrared response of triple concentric quantum ring structures

“…8 As quantum dots, quantum rings can be coupled forming "artificial ring molecules." 9,10 Theoretical studies on double quantum rings coupled vertically [11][12][13][14] and laterally 15,16 have discussed the molecular properties of these systems.…”

Artificial molecular quantum rings under magnetic field influence

“…Such ring-shaped nanostructures can also be coupled in the lateral or vertical configuration forming a "benzene-like" artificial molecule. When QRs structures are coupled they open the avenue of controlling and manipulating some fundamental quantities, as e.g., the electron-electron interaction 7,8,9,10,11,12,13 , the integer and fractional Aharonov-Bohm oscillation 14 , the electron relaxation 15 and the coupling of direct-indirect excitons 16 .…”

“…When QRs' structures are coupled they open the avenue of controlling and manipulating some fundamental quantities, e.g., the electron-electron interaction, [7][8][9][10][11][12][13] the integer and fractional Aharonov-Bohm oscillations, 14 the electron relaxation, 15 and the coupling of direct-indirect excitons. 16 Quantum ring molecules ͑QRMs͒ were synthesized experimentally using MBE technology in the form of vertically stacked layers of self-assembled QRs ͑Refs.…”