Half-Metallic Ferromagnetism in Gd-Doped Ti_1/2Mg_1/2N Alloy: An ab initio Prediction

In this work, we have investigated the electronic and magnetic properties of gadolinium Gd-doped Ti_0.5Mg_0.5N alloy. The supercell of 32 atoms was generated by the Alloy Theoretic Automated Toolkit (ATAT), and then we have used first-principles calculations performed by the full-potential linearized augmented plane wave method based on the spin density functional theory within the generalized gradient approximation of Perdew-Burke-Ernzerhof and the modified Becke-Johnson potential. We have also performed GGA + U calculations describing the strong correlation between the 4f electrons in Gd. Both GGA and mBJ calculations have shown that Ti_0.5Mg_0.5N alloy depicted a semiconductor character with band gaps of 0.403 eV and 1.184 eV, respectively. The calculated atomic-resolved densities of states of Ti₆Gd₂Mg₈N₁₆ alloy predict the half-metallic character (HMs) with ferromagnetic order (FM) using the modified Becke-Johnson potential mBJ. We have also estimated the Curie temperatures by using the Heisenberg model in the mean field approximation.