摘要
Topological metals possess various types of symmetry-protected degenerate band crossings.When a topological metal becomes superconducting,the low-energy electronic excitations stemming from the band crossings located close to the Fermi level may contribute to highly unusual pairing symmetry and superconducting states.In this work,we study the electronic band structure of the time-reversal symmetry breaking superconductor LaNiGa_(2)by means of quantum oscillation measurements.A comprehensive investigation combining angle-resolved high-field de Haas-van Alphen(dHvA)spectroscopy and first-principles calculations reveals the fermiology of LaNiGa_(2)and verifies its nonsymmorphic Cmcm lattice symmetry,which promises nodal band crossings pinned at the Fermi level with fourfold degeneracies.Moreover,such nodal structures,proposed to play a crucial role giving rise to the interorbital triplet pairing,are indeed captured by our d Hv A analysis.Our results identify LaNiGa_(2)as a prototypical topological crystalline superconductor and highlight the putative contribution of low-energy nodal quasiparticles to unconventional superconducting pairing.
基金
supported by the National Natural Science Foundation of China(Grant Nos.12274390,12488201,12204449,and 12122411)
the National Key R&D Program of China(Grant No.2022YFA1602602)
the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0302802)
the Basic Research Program of the Chinese Academy of Sciences Based on Major Scientific Infrastructures(Grant No.JZHKYPT-2021-08)
the Fundamental Research Funds for the Central Universities(Grant No.WK3510000014)。
