First-Principle Simulation of Ferromagnetism in Gd-Doped Mg2X (X = Si, Ge and Sn)

Magnetic phase stability and electronic properties of Gd-doped Mg2X (X = Si, Ge and Sn) were investigated by first-principle calculations based on density functional theory. The present calculations were performed using the Generalized Gradient Approximation (PBE-GGA) and the modified Becke-Johnson (mBJ-GGA). The 4f electrons' behavior has been investigated as a function of the Coulomb repulsion U by varying it from 0 eV to 8 eV. The ground state properties for the pure compounds are consistent with experimental values and other theoretical data. All doped compounds are metallic and ferromagnetic with large Curie temperature values. It was found that both exchange potentials (GGA + U and mBJ + U) provide a better description of the electronic structures of pure and doped systems than regular GGA and mBJ.