Half-metallic ferromagnetism and thermoelectric effect in spinel chalcogenides SrX2S4 (X = Mn, Fe, Co) for spintronics and energy harvesting

Spintronics is an emerging technology in advanced quantum electronics, which has multidirectional applications. In this study, the electronic, magnetic, and thermoelectric characteristics of SrX2S4 (X = Mn, Fe, Co) are computed systematically. The stability in ferromagnetic states is verified by energy released from optimized structures and enthalpy of formation. The Heisenberg model is applied for Curie temperature. The band structures are plotted for both spin & UARR; and & DARR; configurations, which ensure 100% spin polarization and integer magnetic moments. Furthermore, the metallic behavior in spin & UARR; and insulating behavior in spin & DARR; confirm half-metallic ferromagnetism. The crystal field energy, direct exchange energy, indirect exchange energy, and exchange constants indicate that ferromagnetism is due to spin of electrons rather than any clusters of transition metals. The effect of thermoelectric parameters on spin functionality of electrons is addressed to enhance the device reliability. The thermoelectric performance is reported by power factor in the temperature span 100-500 K, which is important for energy harvesting.