The carriers doping effect on electronic and optical behaviors of newly layered Sr1- xHfxFBiS2 alloying materials for light-modulator devices

BiS2-layered superconductors have captivated the colossal attention of the scientific community owing to their structural analogies to other unconventional superconducting materials, termed cuprates and Fe-based superconducting materials. Herein, we inspect how the physical characteristics will be altered in the SrFBiS2 mother compound upon the compositional doping of the hafnium element. The electronic structure characteristics of Sr1−xHfxFBiS2 (x = 0 to 1) are simulated with the virtue of the full-potential linearized augmented plane-wave technique. Accordingly, the evaluated band gap of the parent compound (SrFBiS2) is roughly about 0.88 eV, which vanishes under the substitutional impurity impact of tetravalent (Hf+4). However, a metallic character occurs when Hf is substituted in the SrFBiS2 mother compound, although the bottom conduction band is relocated downward to the Fermi level with the emergence of a viable superconducting state. The band structures and Fermi surface (FS) topology vary obviously with the augmentation of Hf concentration and FS nesting is acquired at the wave vector (π, π, 0). Moreover, the optical characteristics of the explored compounds are probed, while the optical anisotropy in the optical absorption spectra is well marked in the mother material and diminishes through the substitutional Hf impurity effect. The metallic character with Drude-model arises when the incident photon energies span from zero photon energy to infrared spectrum when Hf substitutes Sr in the SrFBiS2 parent compound. The spin orbit coupling (SOC) significantly influences the band structures, Fermi surface topologies, and optical features of these doped systems based on the heavy elements, like Hf or Bi. Hence, the induced nesting FS outcomes may turn Sr1−xHfxFBiS2 into striking materials for newly layered superconductors under the doping effect of hafnium element at low compositional content. Eventually, it is inferred that the SrFBiS2 parent compound would be a potential contender for new superconductivity and may be useful for optical communications and laser devices.