Electronic Structures, and Magnetic and Half-Metallic Properties of Equiatomic Quaternary ScRhTiZ (Z = Si, Ge, Sn) Heusler Alloys

Electronic structures, and the magnetic and half-metallic (HM) properties of equiatomic quaternary ScRhTiZ (Z = Si, Ge, Sn) Heusler (EQH) alloys have been analyzed by first-principles calculations. The results show that equilibrium lattice constants of ScRhTiZ (Z = Si, Ge, Sn) are 6.29 Å, 6.36 Å, and 6.61 Å, respectively. For uniform strain, HM properties are observed with magnetic moments of 2 μ_B in the range of lattice constants of 5.51–6.28 Å, 5.48–6.29 Å, and 5.44–6.26 Å for ScRhTiZ (Z = Si, Ge, Sn), respectively. For tetragonal distortion, the transitions of FM (metal ferromagnetic)-HM-FM-HM-FM states can be obtained for ScRhTiSi by changing the c/a. ScRhTiGe exhibits an FM state and ScRhTiSn undergoes the transitions of FM-FIM (ferrimagnetic)-FM states in its metal nature. Magnetic moments mainly come from Sc and Ti atoms. All three compounds obey the Slater–Pauling rule, M_t = Z_t − 18 in HM nature. The phonon spectra indicate that ScRhTiGe and ScRhTiSn are dynamically stable at equilibrium lattice constants due to no imaginary frequencies. This work can facilitate the exploration of new HM materials in the future application of spintronic devices.