LINEAR CONDUCTANCE AND TUNNEL MAGNETORESISTANCE IN A RASHBA QUANTUM DOT RING COUPLED TO FERROMAGNETIC LEADS

Abstract

Spin-dependent electronic transport through a quantum ring with a quantum dot (QD) inserted in one of its arms is investigated within the Keldysh Green's function theory. We consider that the ring is connected to external ferromagnetic electrodes and there is Rashba spin-orbit interaction (SOI) in the QD. It is found that the anomalous tunnel magnetoresistance (TMR) peak originated from the electron correlations is split into two by the direct coupling between the two leads, with the two normal Coulomb resonances unchanged. The peak position and the magnitude of the conductance and the TMR can be controlled in terms of the SOI-induced phase factor, which can be adjusted by the gate voltage or the structure parameters. The present device should be realizable within present technology and may have practical usage in spintronics.