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.
EPL (Europhysics Letters)
- Pub Date:
- October 2004
- Condensed Matter - Mesoscopic Systems and Quantum Hall Effect
- 4 pages, 4 figures 1 misdirected figure reference corrected mismatch between spin-up/spin-down notation in figure 3-4 and discussion corrected, clarifications in text added