Direct observation of the surface superconducting gap in the topological superconductor candidate β-PdBi2

Abstract

β-PdBi2 is one of the candidates for topological superconductors with a superconducting (SC) transition temperature (Tc) of 5.3 K, in which parity mixing of spin singlet and spin triplet has been anticipated, being crucial for the further understanding of relationship with inversion symmetry and parity mixing in the superconductivity. In this work, we measured the SC gap in high-quality single crystal of β-PdBi2 by using high-resolution laser angle-resolved photoemission spectroscopy below Tc. We found the isotropic SC gaps in momentum space for multiple bands, and observed that the difference between the SC gap of the topological surface bands and the bulk bands is about 0.1 meV, consistent with other experimental results. These direct and quantitative experimental results support the possibility of β-PdBi2 as a topological superconductor, characterized by unique crystal and electronic band structures.

References in corpus (28)

• Topological insulators and superconductors
• Fault-tolerant quantum computation by anyons
• Superconducting proximity effect and Majorana fermions at the surface of a topological insulator
• Classification of topological insulators and superconductors in three spatial dimensions
• Classification of topological quantum matter with symmetries
• Proximity effects in superconductor-ferromagnet heterostructures
• Search for Majorana fermions in superconductors
• Topological Materials: Weyl Semimetals
• Topological superconductors: a review
• Majorana Zero Modes and Topological Quantum Computation
• Superconducting 2D system with lifted spin degeneracy: Mixed singlet-triplet state
• Superconductivty without inversion symmetry: MnSi versus CePt_3Si
• Observation of topological superconductivity on the surface of an iron-based superconductor
• Observation of topological order in a Superconducting doped topological insulator (based on the Bi2Se3 class)
• Superconducting Topological Surface States in Non-centrosymmetric Bulk Superconductor PbTaSe2
• Topologically protected surface states in a centrosymmetric superconductor beta-PdBi2
• Dirac Surface States and Nature of Superconductivity in Noncentrosymmetric BiPd
• Temperature Dependence of the Superfluid Density in a Noncentrosymmetric Superconductor
• Superconductivity at 5.4 K in $\beta$-Bi${}_2$Pd
• Exploring Topological Superconductivity in Topological Materials
• Unconventional superconductivity in the BiS${}_2$-based layered superconductor NdO${}_{0.71}$F${}_{0.29}$BiS${}_2$
• Dirac-Fermion-Induced Parity Mixing in Superconducting Topological Insulators
• Observation of the spin-polarized surface state in a noncentrosymmetric superconductor BiPd
• Superconducting Arcs
• Single gap superconductivity in beta-Bi2Pd
• Doping induced inhomogeneity in high-Tc superconductors
• Surface superconductivity in the topological Weyl semimetal t-PtBi${}_2$
• Experimental evidence of anomalously large superconducting gap on topological surface state of $\beta$-$\mathbf{B}{\mathbf{i}}_2\mathbf{Pd}$ film