Size effects in the exchange coupling between two electrons in quantum wire quantum dots
arXiv:0710.5538 · doi:10.1103/PhysRevB.78.035418
Abstract
We theoretically investigate the properties of a two-electron system confined in the three-dimensional potential of coupled quantum dots formed in a quantum wire. For this purpose, we implement a variational Heitler-London method that minimize the system energies with respect to variational parameters in electron trial wavefunctions. We find that tunneling and exchange couplings exponentially decay with increasing inter-dot distance and inter-dot barrier height. In the quasi-one-dimensional limit achieved by reducing the wire diameter, we find that the overlap between the dots decreases, which results in a drop of the exchange coupling. We also discuss the validity of our variational Heitler-London method with respect to the model potential parameters, and compare our results with available experimental data to find good agreement between the two approaches.
10 pages, 8 figures
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