Effect of interface spin-flip scattering on the spin polarized transport through a quantum dot: Master equation approach

Abstract

We investigate the spin-flip scattering effects on the tunnel magnetoresistance (TMR) through the double barrier magnetic tunnel junction, where a two-energy level quantum dot is sandwiched by two ferromagnetic leads. The spin-flip scattering, which occurs at the interface between the lead and the dot, suppresses the TMR in the bias voltage regions corresponding to the singly occupied (SO) and freely occupied (FO) quantum dot state, respectively. In the FO state, the dot can be occupied by up to two electrons or holes. The suppression of the TMR in the SO region is more significant than that in the FO region in the weak spin-flip regime, i.e., when spin-flip probability η<0.5. When η=0.5, the TMR vanishes for both bias regions. Under strong spin-flip condition, i.e., η>0.5, negative TMR is observed in both occupied regions, with the magnitude occurring in the FO region greater. High asymmetry between the spin-flip strengths of spin-up and spin-down electrons can result in an enhancement in the TMR.