NONEQUILIBRIUM ELECTRON TRANSPORT THROUGH NANOSTRUCTURES: CORRELATION EFFECTS

摘要

We consider electron transport through a quantum dot in the Coulomb blockade regime, when the dot has a total spin 1/2. The low energy physics of this system is modeled by a Kondo-type Hamiltonian describing spin-dependent tunneling and exchange interaction of the electron spins in the leads and the local spin. We show that in the regime of large transport voltage V and magnetic field B with max(V, B) T_K, where T_K is the Kondo temperature, renormalized perturbation theory is valid. Physical quantities such as the differential conductance G and the local magnetization M may be calculated in a controlled way by summing the leading logarithmic terms in each order of perturbation theory. We develop a poor man's scaling renormaliza.tion group treatment for frequency dependent coupling functions, which allows one to calculate G and M to lea-ding order in 1/ln[(V, B)/T_K].