Phonon-assisted tunnelling through a quantum dot coupled to magnetic leads

Spin-polarized transport has been theoretically studied in double barrier tunnelling junctions based on a single level quantum dot interacting with a local phonon mode. It was shown that the electron-phonon interaction gives rise to oscillations of the tunnel magnetoresistance (TMR). In asymmetrical junctions, the polaronic transport through the junction may lead to a significant suppression of the diodelike behaviour. The case of negative effective charging energy has also been analyzed numerically. It was shown in particular that for a mesoscopic diode an interplay between the single-electron cotunnelling and the pair tunnelling processes leads to inversion of TMR.