A First Principles Study of the Electronic Structures and Tetragonal Distortion of the Ti_2NiGa Heusler Alloy

摘要

The electronic structures and tetragonal distortion for the full Heusler compound Ti_2NiGa have been studied by first principles calculations. The results predict that Ti_2NiGa presents half-metallicity within the lattice constants range of 5.70 to 6.50 A together with the integral magnetic moment 3.00μ_B. The total magnetic moment (M_t) and the number of valence electrons (Z_t) of Ti_2NiGa obey the Slater-Pauling (SP) rule of M_t = Z_t - 18 very well. The results of tetragonal distortion indicate that the half-metallicity of Ti_2NiGa alloy can be retained in the range of the c/a ratio from 0.85 to 1.20. Ti(A) atom has dominating contribution to the magnetism of Ti_2NiGa even when the lattice constant and the structure experience large change. In the presence of vacancy defects, Ti_2NiGa can still maintain half-metallicity.