Effect of spin-flip scattering on electrical transport in magnetic tunnel junctions

Zhen-Gang Zhu, Gang Su ∗ , Qing-Rong Zheng, Biao Jin

Department of Physics, The Graduate School of the Chinese Academy of Sciences, P.O. Box 3908, Beijing 100039, China

Received 7 June 2002; accepted 18 June 2002 Communicated by V.M. Agranovich

Abstract By means of the nonequilibrium Green function technique, the effect of spin-flip scatterings on the spin-dependent electrical transport in ferromagnet–insulator–ferromagnet (FM–I–FM) tunnel junctions is investigated. It is shown that Jullière’s formula for the tunnel conductance must be modified when including the contribution from the spin-flip scatterings. It is found that the spin-flip scatterings could lead to an angular shift of the tunnel conductance, giving rise to the junction resistance not being the largest when the orientations of magnetizations in the two FM electrodes are antiparallel, which may offer an alternative explanation for such a phenomenon observed previously in experiments in some FM–I–FM junctions. The spin-flip assisted tunneling is also observed