Topological Superconductivity in an s-wave Superconductor and Its Implication to Iron-based Superconductors

Abstract

In the presence of both space and time reversal symmetries, an s-wave A1g superconducting state is usually topologically trivial. Here we demonstrate that an exception can take place in a type of nonsymmorphic lattice structures. We specify the demonstration in a system with a centrosymmetric space group P4/nmm, the symmetry group that governs iron-based superconductors, by showing the existence of a second-order topological state protected by a mirror symmetry. The topological superconductivity is featured by 2Z degenerate Dirac cones on the (1,0) edge, and Z pairs of Majorana modes at the intersection between the (1,1) and (1,-1) edges. The topological invariance and Fermi surface criterion for the topological state are provided. Moreover, we point out that the previously proposed s-wave state in iron-based superconductors, which features a sign-changed superconducting order parameter between two electron pockets, is such a topological state. Thus, these results not only open a new route to pursue topological superconductivity, but also establish a measurable quantity to settle one long-lasting debate on the pairing nature of iron-based superconductors.

References in corpus (20)

• Non-Abelian Anyons and Topological Quantum Computation
• Superconducting proximity effect and Majorana fermions at the surface of a topological insulator
• Topological Insulators with Inversion Symmetry
• Majorana Fermions and a Topological Phase Transition in Semiconductor-Superconductor Heterostructures
• Classification of topological insulators and superconductors in three spatial dimensions
• Evidence of Majorana fermions in an Al - InAs nanowire topological superconductor
• Topological Crystalline Insulators
• Observation of Majorana Fermions in Ferromagnetic Atomic Chains on a Superconductor
• Electric Multipole Moments, Topological Multipole Moment Pumping, and Chiral Hinge States in Crystalline Insulators
• $(d-2)$-dimensional edge states of rotation symmetry protected topological states
• Reflection symmetric second-order topological insulators and superconductors
• Topological Defects and Gapless Modes in Insulators and Superconductors
• Heavily electron-doped electronic structure and isotropic superconducting gap in AxFe2Se2 (A=K,Cs)
• Zero-energy vortex bound state in the superconducting topological surface state of Fe(Se,Te)
• Surface State Magnetization and Chiral Edge States on Topological Insulators
• Monolayer FeSe on SrTiO${}_3$
• Resilient nodeless $d$-wave superconductivity in monolayer FeSe
• Quasi 1D topological nodal vortex line phase in doped superconducting 3D Dirac Semimetals
• Crystalline symmetry protected helical Majorana modes in the iron pnictides
• Topological crystalline superconductors with linearly and projectively represented $C_n$ symmetry

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• Majorana corner modes and tunable patterns in an altermagnet heterostructure
• Intrinsic first and higher-order topological superconductivity in a doped topological insulator
• Competing Vortex Topologies in Iron-based Superconductors
• Corner- and sublattice-sensitive Majorana zero modes on the kagome lattice
• Sublattice-enriched tunability of bound states in second-order topological insulators and superconductors
• Nodal higher-order topological superconductivity from a ${\mathcal{C}}_4$-symmetric Dirac semimetal
• Superconductivity of anomalous pseudospin
• High-temperature Majorana corner modes in a $d+i{d}^{\prime }$ superconductor heterostructure: Application to twisted bilayer cuprate superconductors
• Twisted nodal wires and three-dimensional quantum spin Hall effect in distorted square-net compounds
• Classification of time-reversal symmetric topological superconducting phases for conventional pairing symmetries
• Majorana corner modes and flat-band Majorana edge modes in superconductor/topological-insulator/superconductor junctions
• Characterization of higher-order topological superconductors using Bott indices
• A proposal for realizing Majorana fermions without external magnetic field in strongly correlated nanowires
• Representation-protected topology of spin-singlet $s$-wave superconductors
• Inducing ${\mathbb{Z}}_2$ Topology in Twisted Nodal Superconductors
• Linear scaling relation between two-dimensional massless Dirac fermion Fermi velocity and Fe-As bond length in iron arsenide superconductor systems
• Theory of Topological Superconductivity in Doped IV-VI Semiconductors
• Intrinsic chiral topological superconductor thin films
• Inversion-symmetric Electron Gases as New Platforms for Topological Planar Josephson Junctions