The surface effect on the thermodynamic stability, half-metallic and optical properties of Co2MnGa(001) films: a DFT study

In this study, the half-metallic properties, thermodynamic stability and optical parameters of the full-Heusler Co2MnGa compound and its four different terminations of Co–Co, Co–Mn, Mn–Ga and Co–Ga from the surface of Co2MnGa (001) have been calculated based on the density functional theory (DFT). The results confirm the ferromagnetic half-metallic behavior with a magnetic moment of 4.08 μB and a gap of 0.32 eV at the Fermi level of Co2MnGa bulk phase having a Cu2MnAl-type structure. The density of states curves showed that all possible terminations from the Co2MnGa (001) surface eliminate the half-metallic behavior except the termination of Mn–Ga case. Moreover, the results indicate that the termination of Mn–Ga with the lowest surface energy is the most stable termination for the application in spintronics. The optical coefficients such as real and imaginary dielectric function, refraction, extinction, energy loss function, optical conductivity and reflections of the bulk and Mn–Ga termination have been calculated and compared.