Vertically coupled double quantum rings under magnetic fields
Francesc Malet
University of Barcelona
Friday, 14 November 2008, 13:30
Seminar room F
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 has the tendency to
flatten the spectra, in the strong coupling limit some clear peaks are still
found even when B \neq 0 that can be
interpretated from the single-particle energy levels analogously as at zero
applied field, namely in terms of closed-shell and Hund's-rule
configurations. 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 a function of B.