Switchable voltage offset in a Heusler alloy-based magnetic tunnel junction

Abstract We investigate the tunneling magnetoresistance (TMR) of the magnetic tunnel junction (MTJ) comprised of the Heusler alloy ( Co 2 MnSi ) and the pinned CoFe to probe the spin polarization of Co 2 MnSi . From the TMR value thus obtained, we estimate 40 % polarization of Co 2 MnSi , much less than 100 % expected for the suspected half metal. Remarkably, upon applying the weak switching magnetic field to the MTJ in the parallel state, our system exhibits a finite open-circuit voltage on the order of several 10 μ V in the anti-parallel state. We have demonstrated that the reversal of magnetic dipolar field induced by the Heusler alloy as a free layer can generate an electromotive force of the same order and can clearly explain the observed polarity and sample size dependence of the voltage offset at zero bias current.