Control of spin on ferromagnetism and thermoelectric properties of Sr(V/Cr)₂S₄; emergent spintronic aspirant

Abstract

Strontium-based spinel chalcogenides show great potential in energy harvesting and spintronics applications. This study extensively examines the electronic, ferromagnetic, and thermoelectric characteristics of SrZ2S4 (Z = V, Cr) spinels. Stability of the cubic phase in a ferromagnetic state is confirmed through formation energy and the energy released upon optimization. Spin polarization and Curie temperature were assessed using density of states (DOSs) analysis and the Heisenberg model, respectively. The investigation of ferromagnetism encompassed exchange energies, the double exchange mechanism, exchange constants, and hybridization processes. The observed reduction in magnetic moment for V/Cr and its redistribution to nonmagnetic (Sr, S) sites suggest that ferromagnetism stems from electron exchange, not from clustering of V/Cr atoms. Furthermore, the study delves into thermoelectric properties, including electrical and thermal conductivities, the Seebeck coefficient (S), and power factor, highlighting their significance for energy applications. The findings reveal ultralow thermal conductivity values, which minimize thermal effects on electron spin, thereby enhancing device longevity. Collectively, these insights underscore the critical role of electron exchange in ferromagnetism and its implications for energy device performance.