Theoretical investigation of electronic and superconducting properties of Beryllium-doped iron-based superconductor: A first-principles study

Abstract

We have performed a comprehensive set of calculations to study the influence of Be-alloying on the electronic and superconducting properties of Iron-Selenium (FeSe). We have considered FeSe1-xBex (where x = 0.0–1.0) and performed density functional theory (DFT) calculations implemented in the Vienna ab initio simulation package (VASP) and SPRKKR electronic structure code. In our study, both spin-unpolarized and spin-polarized calculations using LDA functional have been executed to assess the role of substitutional alloying in this material. We found that these systems are non-magnetic under Be alloying into FeSe. In addition, we calculated Bloch spectral function and Fermi surface of FeSe1-xBex alloys and found that alloying through Be, makes the system disordered and shows its robust nature against alloying. The effect of disorder on the total density of states (DOS) has been investigated and as a result, it shifts the DOS towards higher values at Fermi level. Coherent potential approximation implemented in SPRKKR and supercell method using VASP have been used to handle the substitutional disorder for our studies. Based on the DFT calculations at zero temperature, we found that electrical conductivity decreases by increasing the concentration of Be into FeSe at Se sites. Furthermore, we have also estimated superconducting transition temperature (Tc) for FeSe1-xBex alloys. However, we have experimental evidence for FeSe and FeSe0.94Be0.06 alloys, we have reported the Tc for other concentrations hypothetically and that might be helpful for the synthesis of new superconducting materials, experimentally.