Distortional weak-coupling instability of Bogoliubov Fermi surfaces

Abstract

Centrosymmetric multiband superconductors which break time-reversal symmetry generically have two-dimensional nodes, i.e., Fermi surfaces of Bogoliubov quasiparticles. We show that the coupling of the electrons to the lattice always leads to a weak-coupling instability of such a state towards spontaneous breaking of inversion symmetry at low temperatures. This instability is driven by a Cooper logarithm in the internal energy but the order parameter is not superconducting but distortional. We present a comprehensive symmetry analysis and introduce a measure that allows to compare the strengths of competing distortional instabilities. Moreover, we discuss the instability using an effective single-band model. This framework reveals a duality mapping of the effective model which maps the distortional order parameter onto a superconducting one, providing a natural explanation for the Cooper logarithm and the weak-coupling nature of the instability. Finally, we consider the possibility of a pair-density wave state when inversion symmetry is broken. We find that it can indeed exist but does not affect the instability itself.

16+ pages, 4 figures

References in corpus (11)

• Magnetism, superconductivity, and pairing symmetry in Fe-based superconductors
• Bogoliubov Fermi surfaces in superconductors with broken time-reversal symmetry
• Superconductivity in three-dimensional spin-orbit coupled semimetals
• Topological Blount's theorem of odd-parity superconductors
• A Generic Two-band Model for Unconventional Superconductivity and Spin-Density-Wave Order in Electron and Hole Doped Iron-Based Superconductors
• Inflated nodes and surface states in superconducting half-Heusler compounds
• Hund interaction, spin-orbit coupling and the mechanism of superconductivity in strongly hole-doped iron pnictides
• Spin excitations in the excitonic spin-density-wave state of the iron pnictides
• Resilient nodeless $d$-wave superconductivity in monolayer FeSe
• Majorana surface modes of nodal topological pairings in spin-$\frac{3}{2}$ semi-metals
• Electronic multipoles and multiplet pairs induced from Pomeranchuk and Cooper instabilities of Bogoliubov Fermi surfaces

Cited by in corpus (2)

• Symmetry, nodal structure, and Bogoliubov Fermi surfaces for nonlocal pairing
• Many-body selection rule for quasiparticle pair creations in centrosymmetric superconductors