SPIN BLOCKADE IN NONLINEAR TRANSPORT THROUGH QUANTUM DOTS

The influence of excited levels on the non-linear-transport properties of a quantum dot weakly coupled to ideal leads is studied using a mas ter-equation approach. A quantum-mechanical model for interacting elec trons is used to determine the spectrum of the dot. The current-voltag e characteristic shows Coulomb blockade and additional fine structure that is related to the excited states of the correlated electrons. Asy mmetric coupling to the leads causes asymmetric conductance peaks. It is demonstrated that spin selection rules can lead to regions of negat ive differential conductance.