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<p>The pursuit of viable superconducting and topological materials stands at the forefront of condensed matter physics, as these systems harbor a multitude of exotic quantum phenomena rooted in their distinctive electronic structures. In this study, we employ advanced first-principles density functional theory to systematically probe the topological and superconducting properties of hexagonal TaC and trigonal Ta<sub>2</sub>C. Our electronic structure calculations reveal that hexagonal TaC is a Wely semimetal witch hosts Weyl nodes and a nodal ring without spin–orbit coupling (SOC). Moreover, relativistic trigonal Ta₂C demonstrates a robust nontrivial topological phase characterized by a nonzero <i>Z</i>₂(1; 000) invariant. Phonon dispersion analyses confirm the dynamical stability of both phases, with superconducting critical temperatures <i>T</i><sub>c</sub> of 17.33&#xa0;K for hexagonal TaC and 1.37&#xa0;K for trigonal Ta₂C. The enhanced superconductivity in hexagonal TaC stems from the strong Bardeen-Cooper-Schrieffer electron pairing mediated by Ta-<i>d</i> electrons and significant contributions from both Ta-acoustic and C-optic phonon modes. In contrast, the markedly lower <i>T</i><sub>c</sub> of trigonal Ta<sub>2</sub>C, approximately an order of magnitude less than its hexagonal counterpart and slightly below the experimental measurement of 4.1&#xa0;K, is attributable to weaker electron–phonon coupling and a diminished density of states at the Fermi level.</p>

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Phase-Dependent Topological and Superconductivity Properties of Tantalum-Carbide Systems

  • 期刊论文

  • 发表日期：

    2025年9月12日

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  • Hichem Benaissa,
  • Saleha Azzi,
  • Abdelkader Menad,
  • Mohamed Ferhat

摘要

The pursuit of viable superconducting and topological materials stands at the forefront of condensed matter physics, as these systems harbor a multitude of exotic quantum phenomena rooted in their distinctive electronic structures. In this study, we employ advanced first-principles density functional theory to systematically probe the topological and superconducting properties of hexagonal TaC and trigonal Ta2C. Our electronic structure calculations reveal that hexagonal TaC is a Wely semimetal witch hosts Weyl nodes and a nodal ring without spin–orbit coupling (SOC). Moreover, relativistic trigonal Ta₂C demonstrates a robust nontrivial topological phase characterized by a nonzero Z₂(1; 000) invariant. Phonon dispersion analyses confirm the dynamical stability of both phases, with superconducting critical temperatures Tc of 17.33 K for hexagonal TaC and 1.37 K for trigonal Ta₂C. The enhanced superconductivity in hexagonal TaC stems from the strong Bardeen-Cooper-Schrieffer electron pairing mediated by Ta-d electrons and significant contributions from both Ta-acoustic and C-optic phonon modes. In contrast, the markedly lower Tc of trigonal Ta2C, approximately an order of magnitude less than its hexagonal counterpart and slightly below the experimental measurement of 4.1 K, is attributable to weaker electron–phonon coupling and a diminished density of states at the Fermi level.