  We calculate the nonlinear cotunneling conductance through interacting
quantum dot systems in the deep Coulomb blockade regime using a rate equation
approach based on the T-matrix formalism, which shows in the concerned regions
very good agreement with a generalized master equation approach. Our focus is
on inelastic cotunneling in systems with weakly broken degeneracies, such as
complex quantum dots or molecules. We find for these systems a characteristic
gate dependence of the non-equilibrium cotunneling conductance. While on one
side of a Coulomb diamond the conductance decreases after the inelastic
cotunneling threshold towards its saturation value, on the other side it
increases monotonously even after the threshold. We show that this behavior
originates from an asymmetric gate voltage dependence of the effective
cotunneling amplitudes.
