Spin-triplet pairing state evidenced by half-quantum flux in a noncentrosymmetric superconductor

Abstract

A prime category of superconducting materials in which to look for spin-triplet pairing and topological superconductivity are superconductors without inversion symmetry. It is predicted that the breaking of parity symmetry gives rise to an admixture of spin-singlet / spin-triplet pairing states; a triplet pairing component, being substantial, seems all but guaranteed. However, the experimental confirmation of pair mixing in any particular material remains elusive. In this work, we perform phase-sensitive experiment to examine the pairing state of noncentrosymmetric superconductor $\alpha -$BiPd. The Little-Parks effect observed in mesoscopic polycrystalline $\alpha -$BiPd ring devices reveals the presence of half-integer magnetic flux quantization, which provides a decisive evidence for the spin-triplet pairing state. We find mixed half-quantum fluxes and integer-quantum fluxes, consistent with the scenario of singlet-triplet pair mixing.

References in corpus (22)

• Topological insulators and superconductors
• Unpaired Majorana fermions in quantum wires
• Paired states of fermions in two dimensions with breaking of parity and time-reversal symmetries, and the fractional quantum Hall effect
• Topological superconductors: a review
• Superconducting 2D system with lifted spin degeneracy: Mixed singlet-triplet state
• Odd-Parity Topological Superconductors: Theory and Application to Cu${}_x$Bi${}_2$Se${}_3$
• Superconductivty without inversion symmetry: MnSi versus CePt_3Si
• Fermi Surface Topological Invariants for Time Reversal Invariant Superconductors
• Topological odd-parity superconductors
• Electron Correlation and Pairing States in Superconductors without Inversion Symmetry
• Dirac Surface States and Nature of Superconductivity in Noncentrosymmetric BiPd
• Observation of Andreev bound state and multiple energy gaps in the non-centrosymmetric superconductor BiPd
• Observation of Half-Quantum Flux in Unconventional Superconductor $\beta$-Bi${}_2$Pd
• Observation of the spin-polarized surface state in a noncentrosymmetric superconductor BiPd
• NMR and NQR Studies on Non-centrosymmetric Superconductors Re7B3, LaBiPt, and BiPd
• Anisotropic superconductivity in the noncentrosymmetric BiPd
• Observation of Dirac surface states in the noncentrosymmetric superconductor BiPd
• Unusual Dirac fermions on the surface of noncentrosymmetric $\alpha$ - BiPd superconductor
• Upper critical field of the noncentrosymmetric superconductor BiPd
• Quantum oscillations and a non-trivial Berry phase in the noncentrosymmetric superconductor BiPd
• Weak ferromagnetism in non-centrosymmetric BiPd 4K superconductor
• Correct Brillouin zone and electronic structure of BiPd

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• Tunable quantum interferometer for correlated moiré electrons
• Josephson diode effect in one-dimensional quantum wires connected to superconductors with mixed singlet-triplet pairing
• Nature of the mixed-parity pairing of attractive fermions with spin-orbit coupling in optical lattice
• Little-Parks oscillation and $\mathbf{d}$-vector texture in spin-triplet superconducting rings with bias current
• Flux-periodic oscillations in proximitized core-shell nanowires
• Theory of the Little-Parks effect in spin-triplet superconductors
• Half-quantum flux in spin-triplet superconducting rings with bias current
• Probing the superconducting pairing of the La${}_4$Be${}_{33}$Pt${}_{16}$ alloy via muon-spin spectroscopy
• Temperature dependence of the lower critical field of the noncentrosymmetric superconductor $\alpha$-BiPd
• Ab initio study of orbital-selective superconductivity in $\gamma$-BiPd
• Observation of the crossover from quantum fluxoid to half-quantum fluxoid in a chiral superconducting device