Effect of inserted Cu layer on CoFe/Cu/MgO/CoFe magnetic tunnel junction

Abstract

In this paper, we carried out first-principles calculations based on density functional theory and nonequilibrium Green’s function to investigate the tunneling magnetoresistance effect in CoFe/Cu/MgO/CoFe magnetic tunnel junctions. Insertion of a nonmagnetic Cu layer between the tunnel barrier and the electrode is shown to result in the inverse and oscillation of the tunneling magnetoresistance as a function of the Cu layer at different bias voltage. The inverse phenomenon is discussed in terms of the conductance and the tunneling probability of electron at zero bias voltage. We suggest that the oscillation of tunneling magnetoresistance results from quantum well state formed in nonmagnetic Cu layer which can bring about the multiple scattering of tunneling electrons due to influence of the bias voltage on the oscillation period of the tunneling magnetoresistance.