Spin polarization measurements of Co2Mn (Ga0.5Sn0.5) thin films

Co₂MnGa_0.5Sn_0.5 (CMGS) thin films were epitaxially grown on MgO (0 0 1) substrates by magnetron sputtering and the current spin polarizations of the films with different post annealing conditions were measured by the point contact Andreev reflection method. The film deposited at a substrate temperature of 150 °C had a B2 structure and its spin polarization was estimated to be 59%. The film was ordered to the L2₁ structure by annealing at 600 °C, and the spin polarization was enhanced to 66%. The spin polarization and the intensity of the L2₁ diffraction showed clear correlation, suggesting L2₁ ordering is essential to achieve higher spin polarization of this quaternary Heusler alloy.