First-principles prediction of anisotropic superconductivity in the nodal-line semi-metal TlTaSe2

Abstract

Recent advances in topological quantum materials have spurred significant interest in exploring superconductors that also host nontrivial band topology, as these materials can serve as platforms for novel electronic phases and quantum technologies. TlTaSe 2 is one such non-centrosymmetric, quasi-two-dimensional semimetal with nodal-line topological features protected by mirror-reflection symmetry. In this study, we theoretically predict its superconducting properties using first-principles anisotropic Migdal–Eliashberg theory. Our results indicate that the states at the Fermi, are primarily Ta 5d and Tl 6p orbitals. Thus, exhibiting a multiband electronic structure. Notably, from our calculations, we find two distinct superconducting gaps of 2.15 meV and 4.5 meV on different Fermi surface sheets, arising from strongly anisotropic electron-phonon interactions predominantly involving in-plane vibrations of the Ta and Tl atoms. Using the Allen–Dynes-modified McMillan formula with a Coulomb pseudopotential μ* = 0.16, we predict a superconducting transition temperature Tc of 6.67 K. These findings underscore the significance of TlTaSe 2 as a candidate for topological superconductivity and provide insights into how the interplay between anisotropy, electron-phonon coupling, and nontrivial band topology can be explored for quantum computing and spintronics applications.