Computations on platinum based ternary ferromagnetic half metals for spin valve diodes and green energy technology based thermoelectric

Abstract

The ab initio method commonly known as wavefunction method is used to calculate the structural, mechanical, electronic, magnetic, lattice dynamical and thermoelectric properties of the half metallic half-Heusler alloys VPtZ (Z = Si, Ge, Sn). The equilibrium lattice constants and corresponding ground state energies of the studied alloys are computed in stable ferromagnetic γ-phase with a cubic structure. The electronic properties suggest that the compounds are half metals with indirect band gap having the band energies of 1.02 eV, 1.04 eV and 0.9 eV for VPtSi, VPtGe and VPtSn, respectively, in the spin down channel. The materials have spin magnetic moment of 1 μB, suggest that the materials are suitable for making spintronic devices such as spin valve diodes. Temperature dependent heat transport properties were studied by using classical Boltzmann theory. The materials have high power factor at high temperatures. Thermoelectric performance of the materials is calculated between the temperature range 100–1200 K respectively. The obtained thermoelectric figure of merit for p-type VPtSi, VPtGe and VPtSn are 0.4, 0.7 and 0.3, respectively, at 1200 K. Similarly, the figure of merit obtained for n-type VPtSi, VPtGe and VPtSn are 0.41, 0.75 and 0.3, respectively, at the same temperature. The favourable energy and spin transport properties of these alloys show that they are the potential candidates as thermoelectric for heat energy harvesting and spintronic for magneto electronics applications.