First-principles investigation of elastic, transport, electronic and superconducting properties of noncentrosymmetric Re6X (X=Zr, Hf)

Abstract We have performed first-principles calculations to study the elastic, transport, electronic and superconducting properties of noncentrosymmetric superconductors Re 6 X ( X =  Zr, Hf). The studied superconductors have been found to be elastically stable, brittle in nature, elastically anisotropic and relatively hard material. The calculated Debye temperature, for both compounds, are reasonably close to the experimental values. The Re-5d and Zr-4d/Hf-5d orbitals in Re 6 Zr and Re 6 Hf have a dominant contribution to the total density of states (DOS), with large contributions of interstitials indicating the presence of large interstitial defects in crystal structure. The calculated electron-phonon coupling constant of Re 6 Zr (0.90) and Re 6 Hf (0.84) indicates that both are moderately coupled superconductors. The calculated superconducting transition temperatures of Re 6 Zr and Re 6 Hf are 6.71 K and 4.27 K reasonably close to the experimental values 6.75 K and 6.2 K, respectively.