Magnetoresistance effect in L10-MnGa/MgO/CoFeB perpendicular magnetic tunnel junctions with Co interlayer

The fully perpendicular magnetic tunnel junctions (p-MTJs) based on L1(0)-MnGa and thin CoFeB electrodes with MgO barrier were reported in this letter. A thin Co layer was introduced between the MnGa layer and the MgO barrier layer to investigate interfacial effect on the device's magnetic and transport properties. The magnetoresistance ratio improved significantly due to the Co insertion, and reached 40% at room temperature (80% at 5 K) when the Co thickness was 1.5 nm. Moreover, the junctions with Co interlayer exhibited four low-resistance states in one full cycle rather than two in normal MTJs. The physical origin was discussed by considering the coupling between MnGa and Co layers. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4737000]