Surface Effect on Electronic, Magnetic and Optical Properties of PtMnBi Half-Heusler: A DFT Study

Abstract

We predicted that half-Heusler alloy PtMnBi to be potential candidate for using in spintronic and optoelectronic devices. Using first principle calculations based on density functional theory (DFT) within generalized gradient approximation (GGA), we studied the structural, electronic, magnetic and optical properties of PtMnBi half-Heusler alloy in bulk state and surfaces (001) and for MnBi, PtMn and PtBi terminations. We showed for MnBi termination that if its equilibrium lattice constants an and b are decreased simultaneously by 10%, it becomes a half-metal with a semiconducting gap of 0.2 eV. Also, the magnetic moment of the Mn atom of $4.1\,\,\mu {\kern 1pt} \_{\kern 1pt} {\text{B}}$ on the surface layer of this termination, shows a s light difference compared to the bulk state. The real part of the dielectric function for the incident light in both the xx and zz directions for energies greater than 7.5 eV for all three terminations is the same, and for energies greater than 15 eV they converge to one, indicating that they act as an isotropic insulator and also the refractive index for energies greater than 7.5 eV is less than one, indicating super-luminance phenomenon.