First-principles study of the structure, electronic, magnetic and elastic properties of half-Heusler compounds LiXGe (X = Ca, Sr and Ba)

We first investigate the structural, electronic and magnetic properties of half-Heusler compounds LiXGe (X = Ca, Sr and Ba), by using the first-principles calculations within full-potential local-orbital minimum-basis method. The calculations show that all compounds are half-metallic ferromagnets with the same magnetic moment of 1.00 μB per formula unit and all compounds follow the Slater-Pauling rule: Mtot=(8−Ztot)μB. In the aspects of phonon dispersion, cohesive energy and formation energy, we found all the compounds are found to be stable. Our calculations also show that the half-metallicities can be preserved with lattice constants from −3.6% to 21.4%, −3.8% to 16.1% and −1.2% to 14.7% for LiCaGe, LiSrGe and LiBaGe. At the end the elastic properties for the all three compounds are also reported. •We investigate the structures and properties of three half-Heusler alloys in detail.•All alloys are half-metallic ferromagnets and have a large band gap.•For all alloys, the cubic phase has a better stability than tetragonal phase.