Electronic structure, magnetic and optical properties of quaternary Fe2−xCoxMnAl Heusler alloys

Full-potential linearized augmented plane-wave method is used to calculate electronic structure of L2 1 -ordered Fe 2 MnAl Heusler alloy within WIEN2k code. Exchange correlation is treated using generalized gradient approximation which gives the nearest values to experimental results of lattice constant. On doping Co at Fe site in Fe 2 MnAl in the series Fe 2− x Co x MnAl, nearly 100% spin polarization is realized for x = 0.5, 1 and 1.5 and half-metallic behavior is observed with band gap of ~0.5 eV in minority spin bands. Total magnetic moment increases linearly with increase in value of x and follows the Slater–Pauling curve. Trends of optical conductivity, real and imaginary parts of the dielectric function, reflectivity, energy loss, refractive index, absorption and extinction coefficient with increasing concentration of Co and with incident photon energy point to possible use in solar cell devices and as shielding materials for electromagnetic radiation extending from visible to far UV range.