Exploring Rare-Earth compound ErMn₂Si₂ for thermoelectric and photoelectrochemical applications using Density functional theory

The physical and magnetic properties of the ErMn₂Si₂ compound are investigated with PDE and RPBE functions using the generalized gradient approximations (GGA) approach within the ferromagnetic phase. The obtained structural optimization results carried out using general gradient approximation (GGA) applying Perdew-Burke-Ernzerhof (PBE), which were consistent with the previously experimental findings. The result shows that the ferromagnetic phase of ErMn₂Si₂ exhibits the highest thermodynamic stability. Furthermore, the electronic band structure analysis within the ferromagnetic phase indicates the metallic behaviour of the compound in both spin channels. A hybridization between Er-f and Mn-d states is observed in the valence band along with the Si-p state in the conduction band. Total magnetic moments confirm the ferromagnetic characteristics of the ternary inter-metallic ErMn₂Si₂ compound. In this study, analysis of the Seebeck coefficient was discussed in detail. The electrical and thermal conductivities of the compound were investigated in a broad range of temperatures (0 to 600 K). Additionally, we present the quasi-harmonic model-calculated thermodynamic characteristics as a function of pressure (0–60 GPa) and temperature (0–1200 K). Evaluating the optical characteristics, ErMn₂Si₂ shows strong dielectric material characteristics in the visible regions of the electromagnetic spectrum. Further, the figure of merit (ZT) was probed. The enhanced ZT values of ErMn₂Si₂ compounds at elevated temperatures make it a potential candidate for high-temperature applications especially for thermoelectric devices. These results may be useful for further investigations of the rear-earth substituted ErMn₂Si₂-based compounds for various applications.