Topological surface superconductivity in doped Weyl loop materials

Abstract

We study surface superconductivity involving the `drumhead' surface states of (doped) Weyl loop materials. The leading weak coupling instability in the bulk is toward a chiral superconducting order, which fully gaps the Fermi surface. In this state the surface also becomes superconducting, with $p+ip$ symmetry. We show that the surface SC state is "topological" as long as it is fully gapped, and the system traps Majoarana modes wherever a vortex line enters or exits the bulk. In contrast to true 2D $p+ip$ superconductors, these Majorana zero modes arise even in the "strong pairing" regime where the chemical potential is entirely above/below the drumhead. We also consider conventional $s$-wave pairing, and show that in this case the surface hosts a flat band of charge neutral Majorana fermions, whose momentum range is given by the projection of the bulk Fermi surface. Weyl loop materials thus provide access to new forms of topological superconductivity.

9 pages, 5 figures

References in corpus (9)

• Superconducting proximity effect and Majorana fermions at the surface of a topological insulator
• Weyl semimetal phase in non-centrosymmetric transition metal monophosphides
• Topological confinement in bilayer graphene
• Potential ring of Dirac nodes in a new polymorph of Ca${}_3$P${}_2$
• Line of Dirac Nodes in Hyper-Honeycomb Lattices
• Crossed surface flat bands of Weyl semimetal superconductors
• Low Carrier Density Metal Realized in Candidate Line-Node Dirac Semimetals CaAgP and CaAgAs
• Topological spinon semimetals and gapless boundary states in three dimensions
• Topological superconductors as nonrelativistic limits of Jackiw-Rossi and Jackiw-Rebbi models

Cited by in corpus (14)

• Nonsymmorphic-symmetry-protected hourglass Dirac loop, nodal line, and Dirac point in bulk and monolayer $X_3$SiTe${}_6$ ($X=$ Ta, Nb)
• Signatures of Weyl fermion annihilation in a correlated kagome magnet
• What's knot to like? Observation of a linked loop quantum state
• Emergent anomalies and generalized Luttinger theorems in metals and semimetals
• Nodal topological superconductivity in nodal-line semimetals
• $R$RuB${}_2$ ($R$=Y, Lu), topological superconductor candidates with hourglass-type Dirac ring
• Topological order in interacting semimetals
• Unusual Resistive Transitions in the Nodal-Line Semimetallic Superconductor NaAlSi
• Superconductivity and a van Hove singularity confined to the surface of a topological semimetal
• Work statistics across a quantum critical surface
• Weyl Nodal-Ring Semimetallic Behavior and Topological Superconductivity in Crystalline Forms of Su-Schrieffer-Heeger Chains
• Observation of a flat and extended surface state in a topological semimetal
• Fragile topology in nodal-line semimetal superconductors
• Surface magnon spectra of nodal loop semimetals