Electronic structure of the surface superconducting Weyl semimetal PtBi${}_2$

Abstract

Trigonal PtBi${}_2$ is a layered semimetal without inversion symmetry, featuring 12 Weyl points in the vicinity of the Fermi energy. Its topological Fermi arcs were recently shown to superconduct at low temperatures where bulk superconductivity is absent. Here, we perform first-principles calculations to investigate in detail the bulk and surface electronic structure of PtBi${}_2$, and obtain the spin texture as well as the momentum-dependent localization of the arcs. Motivated by the experimentally observed recovery of inversion symmetry under pressure or upon doping, we interpolate between the two structures and determine the energy and momentum dependence of the Weyl nodes. For deeper insights into the surface superconductivity of PtBi${}_2$, we construct a symmetry-adapted effective four-band model that accurately reproduces the Weyl points of PtBi${}_2$. We supplement this model with an analysis of the symmetry-allowed pairings between the Fermi arcs, which naturally mix spin-singlet and spin-triplet channels. Moreover, the presence of surface-only superconductivity facilitates an intrinsic superconductor-semimetal-superconductor Josephson junction, with the semimetallic phase sandwiched between the two superconducting surfaces. For a phase difference of $\pi$, zero-energy Andreev bound states develop between the two terminations.

14 pages, 13 figures

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• Intrinsic surface superconducting instability in Type-I Weyl Semimetals
• Bogoliubov Fermi surfaces from pairing of emergent $j=3/2$ fermions on the pyrochlore lattice
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Cited by in corpus (10)

• Fermi arcs dominating the electronic surface properties of trigonal PtBi${}_2$
• Phonon-mediated intrinsic topological superconductivity in Fermi arcs
• Self-consistent surface superconductivity in time-reversal symmetric Weyl semimetals
• Topological nodal $i$-wave superconductivity in PtBi${}_2$
• Ginzburg-Landau theory for unconventional surface superconductivity in PtBi${}_2$
• Interplay between inversion and translation symmetries in trigonal PtBi${}_2$
• Gapless Topological Peierls-like instabilities in more than one dimension
• Higher-order topological superconductivity in type-II time-reversal-symmetric Weyl semimetals with a hybrid pairing
• Mechanism for Nodal Topological Superconductivity on PtBi${}_2$ Surface
• Beyond spin-1/2: Multipolar spin-orbit coupling in noncentrosymmetric crystals with time-reversal symmetry