Interactions and Interference in Quantum Dots: Kinks in Coulomb Blockade Peak Positions

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Abstract
We investigate the spin of the ground state of a geometrically confined many-electron system. For atoms, this problem is simplified because of shell structure-- the spin is prescribed by the well-known Hund's rule. In contrast, quantum dots provide a controllable setting for studying the interplay of quantum interference and electron-electron interactions in general cases. In a generic confining potential, the shell-structure argument suggests a singlet ground state for an even number of electrons. We show, however, that interaction among the electrons produces accidental occurrences of spin-triplet ground states, even for weak interaction, a limit which we analyze explicitly. Variaton of an external parameter causes sudden switching between the singlet and triplet states and hence a kink in the conductance which can be observed experimentally.

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