Spin splitting in open quantum dotsM. Evaldsson1, I. V. Zozoulenko1, M. Ciorga2, P. Zawadzki2 and A. S. Sachrajda2
1 Department of Science and Technology (ITN), Linköping University 601 74 Norrköping, Sweden
2 Institute for Microstructural Science, National Research Council K1A 0R6, Ottawa, Canada
received 13 May 2004; accepted in final form 19 August 2004
We demonstrate that the magnetoconductance of small lateral quantum dots in the strongly coupled regime (i.e. when the leads can support one or more propagating modes) shows a pronounced splitting of the conductance peaks and dips which persists over a wide range of magnetic fields (from zero field to the edge-state regime) and is virtually independent of the magnetic field strength. Our numerical analysis of the conductance based on the Hubbard Hamiltonian demonstrates that this is essentially a many-body/spin effect that can be traced to a splitting of degenerate levels in the corresponding closed dot. The above effect in open dots can be regarded as a counterpart of the Coulomb-blockade effect in weakly coupled dots, with the difference, however, that the splitting of the peaks originates from interactions between electrons of opposite spin.
73.23.Ad - Ballistic transport.
73.21.La - Quantum dots.
72.25.Dc - Spin polarized transport in semiconductors.
© EDP Sciences 2004