First principle investigation of half metallic ferromagnetism and thermoelectric behavior of MgSm2(S/Se)4 spinels for spintronic and energy harvesting applications

Abstract

Density functional theory investigates the spin-dependent structural, electronic, magnetic, and thermoelectric properties of MgSm2 × 4 (X = S, Se). The optimization uses PBEsol-GGA to compute the lattice constant, bulk modulus, and energies. The Heisenberg model has been applied to calculate the Curie temperature which shows ferromagnetism above room temperature. The negative values of formation energy confirm their thermodynamic stability. The half-metallic ferromagnetism (HMF) is observed from the metallic character in the spin-up channel and insulating behaviour in the spin-down channel. The density of states plots indicates that 4f-states of Sm, 3s states of Mg and 3p/4p states of S/Se play a crucial role in forming band edges. The computation of exchange energies and exchange magnetic constants has assisted in determining these spinels' ferromagnetic and 100 % spin polarized nature. The magnetic moments (MM) arise from the p-f hybridization of Sm and X atoms. The robust half-metallicity and high Curie temperature make the studied materials suitable for spintronic applications. In addition, calculating temperature dependent thermoelectric parameters reveals an extra degree of applications of these materials for thermoelectric devices.