Singlet-triplet transitions in highly correlated nanowire quantum dots

Abstract

We consider a quantum dot embedded in a three-dimensional nanowire with tunable aspect ratio a. A configuration interaction theory is developed to calculate the energy spectra of the finite ID quantum dot systems charged with two electrons in the presence of magnetic fields B along the wire axis. Fruitful singlet-triplet transition behaviors are revealed and explained in terms of the competing exchange interaction, correlation interaction, and spin-Zeeman energy. In the high aspect ratio regime, the singlet-triplet transitions are shown designable by tuning the parameters a and B. The transition also manifest the highly correlated nature of long nanowire quantum dots. (C) 2009 Elsevier B.V. All rights reserved.