Hamburg 2001 – scientific programme

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HL: Halbleiterphysik

HL 2: Symposium: Kondo Physics in Quantum Dots

HL 2.1: Fachvortrag

Monday, March 26, 2001, 10:30–11:00, S2

Theory of Kondo Effects in Quantum Dots — •Leonid Glazman — Theoretical Physics Institute, Physics 148, University of Minnesota, 116 Church St, SE Minneapolis, MN 55455 USA

We review theory of the low-temperature electron transport through quantum dots. An electron changes the charge of the dot in the process of passing through it. The resulting Coulomb blockade phenomenon nominally leads to a suppression of the conductance. However, if the ground state of the dot is spin-degenerate, resonant tunneling of electrons becomes possible, despite the Coulomb blockade. The resonance, which enhances the conductance through the dot, develops at low temperatures due to the Kondo effect. Under the conventional conditions, an applied magnetic field destroys the Kondo resonance by quenching the fluctuations of the localized spin. In the case of quantum dots, however, application of a magnetic field may induce a transition between the singlet and triplet spin states of the dot. The degeneracy re-emerges at the point of transition, thus creating the conditions for a generalized Kondo effect. We discuss the manifestations of the conventional and generalized Kondo effects in quantum dots.