The study on the effect of Tellurium (Te) on the electronic structure of Iron Selenium (FeSe)

Abstract

In this work we present the effect of tellurium (Te) on band structure, DOS and superconductivity of FeSe(for x=0.25 and x=0.5). The electronic structure calculations are performed using the density functional theory (DFT) as implemented in QUANTUM ESPRESSO (QE). All calculations of FeSe1−xTex were done for the space group P4/nmm with non-spin polarized orbitals with lattice parameters a=b=3.765[a.u], c=5.51[a.u]. We reproduced the known band structure for FeSe and FeTe. Based on the carefully prepared input file we produced the band structure for x=0.25 and x=0.5. The band structures are highly affected at x=0.5. We observed that there is a flat band from M to Γ direction. We calculated the DOS at the Fermi level to be for FeSe0.5Te0.5 which is higher than that of FeSe which was reported to be 2.69 . The FeSe0.75Te0.25 shows no superconductivity. Superconducting critical temperature TC for FeSe0.5Te0.5 was calculated by introducing our DOS result in to the McMillan equation. The result showed that the TC is increased to 12.08K. We concluded that the effect of substituting Te in FeSe increases the DOS and TC. The results are in agreement with the experimental reports. We also predict that Te substitution is hole dopping.