Insight into Electronic, Optoelectronic and Thermoelectric Properties of Full-Heusler X2TaSi (X = Rb, K): First-Principles Calculations

Abstract

In this study, we have examined structural, electronic, magnetic, optic, thermoelectric, and elastic properties of full-Heusler alloys X₂TaSi (where X = Rb and K). First-principles calculations were performed to analyze the data, with the full-potential linearized augmented plane-wave method serving as the underlying basis. This method is firmly rooted in density functional theory. The calculations were executed using the WIEN2k code, firstly with the generalized gradient approximation and then with its modified Becke–Johnson version, which is commonly used to enhance the band gap values and align them with experimental findings, if available. The results related to the electronic and magnetic properties indicate that the full-Heusler alloys X₂TaSi (where X = Rb and K) exhibit half-metallic ferromagnetic behavior. Optical results demonstrated that the Heusler compounds K₂TaSi and Rb₂TaSi exhibit strong absorption and reflectivity in the ultraviolet range. These findings suggest that these compounds have significant potential for utilization in optical and optoelectronic devices within this spectrum. The findings of thermoelectric properties indicate that the X₂TaSi alloys (where X = Rb and K) are N-type semiconductors, as evidenced by their negative Seebeck coefficients. These alloys also exhibit high ZT values close to unity at low and medium temperatures. The elastic properties of the Rb₂TaSi compound suggest that it is mechanically stable and relatively ductile. In contrast, the K₂TaSi compound exhibits a relatively brittle nature.