Coherent effects in magnetotransport through Zeeman-split levels

We study nonequilibrium electronic transport through a quantum dot or an impurity weakly coupled to ferromagnetic leads. Based on the rate equation formalism we derive the noise spectra for the transport current. We show that, due to quantum interference between different spin components of the current, the spectrum develops peaks or dips at frequencies corresponding to the Zeeman splitting in the quantum dot. A detailed analysis of the spectral structure of the current is carried out for noninteracting electrons as well as for the regime of Coulomb blockade.