New magnesium based half-metallic ferromagnetic chalcogenide MgFe2Z4 (Z = S, Se) spinels; a promising materials for spintronic applications

Abstract

Abstract This article focuses on the physical properties of MgFe2Z4 (Z = S, Se) spinels investigated by employing density functional theory calculations. To explore the magnetic and electronic properties, WIEN2k code was executed whereas thermoelectric properties were studied using the BoltzTraP. The determined negative formation energies and positive phonon frequencies show that the system under investigation is stable. The lowest possible ground state energies clearly indicate that spinels lie in ferromagnetic state. Studied spinels illustrated half-metallic nature upon employing the calculations of density of states (DOS) and spin-polarized band structures (BS). Ferromagnetic (FM) state was found to be stable ground state. Observation of ferromagnetism in these compounds was ensured by exchange energies, Jahn-Teller energy and hybridization and is attributed to electron spin in place of Fe2+ clustering. Curie temperature and spin polarization of these compounds is also comprehensively investigated in this study. Analysis of the thermoelectric properties showed a good fit between the ratio of electrical (σ/τ) and thermal conductivity (κ e/τ). Thermoelectric efficiency of studied compounds is found to be appropriate as demonstrated by the thermoelectric power factors.