Negative differential conductance induced by spin-charge separation

Spin-charge states of correlated electrons in a one-dimensional quantum dot attached to interacting leads are studied in the nonlinear transport regime. With nonsymmetric tunnel barriers, regions of negative differential conductance induced by spin-charge separation are found. They are due to a correlation-induced trapping of higher-spin states without magnetic field and are associated with a strong increase in the fluctuations of the electron spin.