Study of room temperature ferromagnetism, mechanical, thermodynamic, and thermoelectric aspects of BePr₂X₄ (X = S, Se, Te) for spintronic and energy devices

Spintronics is a growing technology that controls the functionality of quantum electronic devices by the spin of electrons rather than traditional electronics. In the current article, the structural, electronic, magnetic, thermoelectric, and mechanical aspects of rare-earth-based spinel chalcogenides BePr₂×₄ (X = S, Se, Te) are addressed comprehensively by density functional theory. The formation energy and energy release in the optimization of these spinels in ferromagnetic, antiferromagnetic, and paramagnetic states confirm the stability of ferromagnetic states. The Heisenberg model and band structure (BS) analysis reports the Curie temperature (T_c > 300K) and complete spin polarization (P = 1.0). The BS and density of states reveal a ferromagnetic semiconducting nature. The strong hybridization between 4f-Pr states and p-states of anions (S–Te) confirms the role of electrons' spin rather than clustering of Pr ions. Moreover, the shifting of magnetic moments from Pr to other sides and negative exchange constants are also responsible for the exchange of electrons' spin. Thermoelectric and thermodynamic parameters are also investigated in the temperature range from 100 to 600K. The figure of merit (0.77, 0.95, 1.20) also makes them promising materials for energy harvesting. Finally, the elastic constants are calculated to ensure the ductile nature, large specific heat, melting, and Debye temperatures with ultralow lattice thermal conductivity.