Topology and symmetry of surface Majorana arcs in cyclic superconductors

Abstract

We study the topology and symmetry of surface Majorana arcs in superconductors with nonunitary "cyclic" pairing. Cyclic $p$-wave pairing may be realized in a cubic or tetrahedral crystal, while it is a candidate for the interior ${}^3{P}_2$ superfluids of neutron stars. The cyclic state is an admixture of full gap and nodal gap with eight Weyl points and the low-energy physics is governed by itinerant Majorana fermions. We here show the evolution of surface states from Majorana cone to Majorana arcs under rotation of surface orientation. The Majorana cone is protected solely by an accidental spin rotation symmetry and fragile against spin-orbit coupling, while the arcs are attributed to two topological invariants: the first Chern number and one-dimensional winding number. Lastly, we discuss how topologically protected surface states inherent to the nonunitary cyclic pairing can be captured from surface probes in candidate compounds, such as U${}_{1-x}$Th${}_x$Be${}_{13}$. We examine tunneling conductance spectra for two competitive scenarios in U${}_{1-x}$Th${}_x$Be${}_{13}$---the degenerate $E_u$ scenario and the accidental scenario.

15 pages, 11 figures

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Cited by in corpus (10)

• Spin-polarized phases of ${}^3{P}_2$ superfluids in neutron stars
• Spontaneous magnetization in unitary superconductors with time reversal symmetry breaking
• Surface density of states and tunneling spectroscopy of a spin-3/2 superconductor with Bogoliubov Fermi Surfaces
• Spin-Nernst Effect in Time-Reversal-Invariant Topological Superconductors
• Spin caloritronics as a probe of nonunitary superconductors
• Anomalous acoustoelectric effect induced by clapping modes in chiral superconductors
• Strongly interacting matter in extreme magnetic fields
• Symmetry classification of uniform states in spin-2 Bose-Einstein condensates and neutron ${}^3{P}_2$ superfluids
• Impurity bands, line-nodes, and anomalous thermal Hall effect in Weyl superconductors
• Emergent chirality and superfluidity of parity-doubled baryons in neutron stars