Fragile topology in nodal-line semimetal superconductors

Abstract

We study the band topology of the superconducting nodal-line semimetal (SC-NLSM) protected by the inversion symmetry with and without the spin-orbital coupling. Without the spin-orbital coupling, both the $s$-wave SC-NLSM and the chiral $p$-wave SC-NLSM are topologically nontrivial and can be described by the nonzero winding number. Based on the Wilson loop method, we verify that they are both the fragile topological superconductors, namely, their nontrivial band topologies can be moved off by coupling to additional topologically trivial bands. The fragile topological phase persists in spinful system with the time-reversal symmetry when a spin-orbital coupling term is added. For the spinful system, both the $p$-wave SC-NLSM and the $s$-wave SC-NLSM are second-order fragile topological superconductors. We propose that the fragile topology in the SC-NLSM system depends strongly on the degeneracy of the Majorana zero modes and the parity of the superconducting gap function. Interestingly, in presence of a vortex line, the spinful $s$-wave SC-NLSM system hosts two pairs of stable Majorana zero modes in the vortex core.

12 pages, 9 figures, Supplementary Material: 3 pages

References in corpus (15)

• Topological Insulators with Inversion Symmetry
• Electric Multipole Moments, Topological Multipole Moment Pumping, and Chiral Hinge States in Crystalline Insulators
• Topological nodal line semimetals
• The space group classification of topological band insulators
• Classification of reflection symmetry protected topological semimetals and nodal superconductors
• Topological Nodal Line Semimetals in CaP3 family of materials
• Topological surface states in nodal superconductors
• Hierarchy of higher-order topological superconductors in three dimensions
• Topological surface superconductivity in doped Weyl loop materials
• Quasi 1D topological nodal vortex line phase in doped superconducting 3D Dirac Semimetals
• Emergence of Topological Nodal Lines and Type II Weyl Nodes in Strong Spin--Orbit Coupling System InNbX2(X=S,Se)
• Competing Vortex Topologies in Iron-based Superconductors
• Quantum oscillations in the non-centrosymmetric superconductor and topological nodal-line semimetal PbTaSe${}_2$
• Superconducting and Topological Properties in Centrosymmetric PbTaS2 Single Crystals
• Enhanced anisotropic superconductivity in the topological nodal-line semimetal InxTaS2

Cited by in corpus (3)

• Majorana corner states in an attractive quantum spin Hall insulator with opposite in-plane Zeeman energy at two sublattice sites
• Higher order topological state induced by $d$-wave competing orders in high-T${}_c$ superconductor based heterostructure
• Nodal-line semimetals and their variance