Designing new tetragonal Heusler materials using V, Cr, Fe and Ni doped Ti2CoGa: A first-principles study

Abstract

In this work, the structure and potential tetragonal distortion (TD) properties of Ti2CoGa and its M−doped (M = V, Cr, Mn, Fe, Ni) system are studied in detail by first-principles calculations. The result shows that Ti2CoGa alloy should crystalize in cubic L21-type structure and no tetragonal distortion is discovered, which limits its application. Attempts are made to seek new tetragonal Heusler materials by replacing Ti or Co atoms in Ti2CoGa with element M (M = V, Cr, Mn, Fe, Ni). It is found that all the Ti2Co1−xMxGa (x = 0.25, 0.5, 0.75; M = V, Cr, Mn, Fe, Ni) compounds tend to form L21 structure, and only Ti2Co1−xNixGa has the possibility of TD when x > 0.29. For Ti2−xMxCoGa (x = 0.25, 0.5, 0.75) system, the increase of the doping amount results in the cubic ground state of the alloy turning from L21 to XA structure. Furthermore, energy curves with different structures show that the tendency of TD in the alloy can be excited after substitution V (x = 0.29–0.50), Cr (x = 0.31–0.43) and Fe (x = 0.21–0.29) for partial Ti. This research can inspire us to search and realize new tetragonal Heusler materials by suitable doping in ternary Heusler alloys.