The prominent characteristics of stable ferromagnetic spinels MnY2(S/Se)4 for optoelectronic and thermoelectric applications: DFT plus U plus mBJ study

초록

The rising demand of advanced materials with significant features in the fields of optoelectronic as well as thermoelectric is essential. The prominent characteristics of spinels make them attractive for the researchers and to be extensively analyzed materials. This study focus to explore physical characteristics including mechanical, optoelectronic, transport and magnetic of MnY2(S/Se)4 by applying WIEN2k and BoltzTrap computational tools. These materials have space group Fd3m with cubic structure. The thermodynamic and mechanical stability is evaluated through their formation energy (triangle Hf) and elastic stiffness constants. The Born stability criteria validates the mechanical stability, whereas negative formation energies confirm the thermodynamic stability of the studied materials. The density of states (DOS) and spin-polarized band structure corroborate direct bandgap along with semiconducting nature. The magnitude of static dielectric constants is observed as 6.5 and 8.5 for MnY2S4 and MnY2Se4, respectively. Maximum absorption of light occurs along a wide range from visible to ultraviolet range with peak value in the UV region of the investigated compositions. The existence of manganese (Mn) ions generates the ferromagnetic (FM) behavior in these materials along with strong local magnetic moment contribution. The transport analysis has been done within temperatures from 300 to 800 K. The increasing trend of electrical and thermal conductivities as a function of temperature along with high Seebeck coefficients within the range of 242-251 mu V/K is observed for both examined materials but the figure of merit (ZT) remains almost constant within the temperature range. Overall, our findings suggest that suitability of these materials for thermoelectric as well as optoelectronic applications.

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