Room temperature ferromagnetism and thermoelectric behavior of calcium based spinel chalcogenides CaZ₂S₄ (Z = Ti, V, Cr, Fe) for spintronic applications

The electronic, magnetic, and thermoelectric properties of CaZ₂S₄ (Z = Ti, V, Cr, Fe) are explored comprehensively. The stability in the ferromagnetic state (FM) has been ensured by energy released from optimized structures and enthalpy of formation (ΔH). The Heisenberg classical model has been used to calculate Curie temperature (Tc). The band structures (BS), as well as densities of states (DOS), are analyzed to explore half-metallic ferromagnetism and 100% spin polarization. The Δx(pd) (exchange energy) overcome Δ_CF (Crystal field energy) because of ferromagnetism prompted by strong hybridization. The negative Δx(pd) and exchange constant N₀β reduced exchange energy that satisfies the double exchange model. The thermoelectric properties of the studied compounds are elaborated by estimating electrical conductivity, thermal conductivity, and the Seebeck coefficient. The increase in power factor with the CaFe₂S₄ has been noted while other spinels have very low power factor.