Nonequilibrium transport through a Kondo dot: decoherence effects

Abstract. Electron transport through a quantum-dot in the Coulomb blockade regime is modeled by a Kondo-type hamiltonian describing spin-dependent tun-neling and exchange interaction with the local spin. We consider the regime of large transport voltage V and magnetic field B with max(V,B) TK, the Kondo temperature, and show that a renormalized perturbation theory can be formulated describing the local magnetization M and the differential conductance G quantita-tively. Based on the structure of leading logarithmic corrections in bare perturbation theory we argue that the perturbative renormalization group has to be generalized to allow for frequency dependent coupling functions. We simplify the full RG equa-tions in the spirit of poor man’s scaling and calculate M and G in leading order of 1/n[(V,B)/TK]. The transport of electrons through a quantum dot in the limit of weak coupling to the leads is dominated by Coulomb interaction effects, forcing in-tegral electron charge on the dot [1]. Adding or removing electrons requires a large energy, the charging energy Ec, and thus transport is blocked (Coulom