Dirac Surface States and Nature of Superconductivity in Noncentrosymmetric BiPd

Abstract

In non-magnetic bulk materials, inversion symmetry protects the spin degeneracy. If the bulk crystal structure lacks a centre of inversion, however, spin-orbit interactions lift the spin degeneracy, leading to a Rashba metal whose Fermi surfaces exhibit an intricate spin texture. In superconducting Rashba metals a pairing wavefunction constructed from these complex spin structures will generally contain both singlet and triplet character. Here we examine the possible triplet components of the order parameter in noncentrosymmetric BiPd, combining for the first time in a noncentrosymmetric superconductor macroscopic characterization, atomic-scale ultra-low-temperature scanning tunnelling spectroscopy, and relativistic first-principles calculations. While the superconducting state of BiPd appears topologically trivial, consistent with Bardeen-Cooper-Schrieffer theory with an order parameter governed by a single isotropic s-wave gap, we show that the material exhibits Dirac-cone surface states with a helical spin polarization.

replaced by published version

References in corpus (8)

• Classification of topological insulators and superconductors in three spatial dimensions
• Topological Phases of Noncentrosymmetric Superconductors: Edge States, Majorana Fermions, and the Non-Abelian Statistics
• Anomalous Andreev bound state in non-centrosymmetric superconductors
• Majorana Fermions in Nodal Superconductors: Gapless Topological Phase
• Surface bound states and spin currents in non-centrosymmetric superconductors
• Andreev bound states and tunneling characteristics of a non-centrosymmetric superconductor
• Gap structure in noncentrosymmetric superconductors
• Observation of Andreev bound state and multiple energy gaps in the non-centrosymmetric superconductor BiPd

Cited by in corpus (27)

• A comprehensive review on topological superconducting materials and interfaces
• Simultaneous Nodal Superconductivity and Time-Reversal Symmetry Breaking in the Noncentrosymmetric Superconductor CaPtAs
• Superconducting and normal-state properties of the noncentrosymmetric superconductor Re6Zr
• Type-I superconductivity in noncentrosymmetric NbGe${}_2$
• CaPtAs: a new noncentrosymmetric superconductor
• Electron-phonon coupling and pairing mechanism in $\beta$--Bi${}_2$Pd centrosymmetric superconductor
• Structure and superconductivity in the binary Re${}_{1-x}$Mo${}_x$ alloys
• Observation of Dirac surface states in the noncentrosymmetric superconductor BiPd
• Unusual Dirac fermions on the surface of noncentrosymmetric $\alpha$ - BiPd superconductor
• Electronic and lattice properties of non-centrosymmetric superconductors ThTSi (T = Co, Ir, Ni, and Pt)
• Unconventional superconducting properties of noncentrosymmetric Re5.5Ta
• Time-reversal symmetry breaking in Re-based superconductors: Recent developments
• Nodeless superconductivity in the centro- and noncentrosymmetric rhenium-boron superconductors
• Evidence of fully-gapped superconductivity in NbReSi: A combined $\mu$SR and NMR study
• Evidence for the coexistence of time-reversal symmetry breaking and Bardeen-Cooper-Schrieffer-like superconductivity in La${}_7$Pd${}_3$
• $R$RuB${}_2$ ($R$=Y, Lu), topological superconductor candidates with hourglass-type Dirac ring
• Unconventional pressure dependence of the superfluid density in the nodeless topological superconductor $\alpha$-PdBi${}_2$
• Superconducting ground state of nonsymmorphic superconducting compound Zr${}_2$Ir
• Exceptional Dirac states in a non-centrosymmetric superconductor, BiPd
• Fully-gapped superconductivity and topological aspects of the noncentrosymmetric TaReSi superconductor
• Nodeless superconductivity in the noncentrosymmetric ThIrSi compound
• Fermi surface and band structure of BiPd from ARPES studies
• Muon spin rotation and relaxation study on topological noncentrosymmetric superconductor PbTaSe${}_2$
• Topological Surface Superconductivity Induced by Hydrostatic Pressure-Enhanced Antisymmetric Spin-Orbit Coupling in Non-Centrosymmetric Superconductor PbTaSe2
• Temperature dependence of the lower critical field of the noncentrosymmetric superconductor $\alpha$-BiPd
• Discovery of the topological surface state in a noncentrosymmetric superconductor BiPd
• SnAs: a 4K weak type-II superconductor with non-trivial band topology