Tuning the Parity Mixing of Singlet-Septet Pairing in a Half-Heusler Superconductor

Abstract

In superconductors, electrons with spin $s=1/2$ form Cooper pairs whose spin structure is usually singlet ($S=0$) or triplet ($S=1$). When the electronic structure near the Fermi level is characterized by fermions with angular momentum $j=3/2$ due to strong spin-orbit interactions, novel pairing states such as even-parity quintet ($J=2$) and odd-parity septet ($J=3$) states become allowed. Prime candidates for such exotic states are half-Heusler superconductors, which exhibit unconventional superconducting properties, but their pairing nature remains unsettled. Here we show that the superconductivity in the noncentrosymmetric half-Heusler LuPdBi can be consistently described by the admixture of isotropic even-parity singlet and anisotropic odd-parity septet pairing, whose ratio can be tuned by electron irradiation. From magnetotransport and penetration depth measurements, we find that carrier concentrations and impurity scattering both increase with irradiation, resulting in a nonmonotonic change of the superconducting gap structure. Our findings shed new light on our fundamental understanding of unconventional superconducting states in topological materials.

11 pages, 9 figures, to be published in Phys. Rev. X

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Cited by in corpus (11)

• Antiferromagnetic spin fluctuations and unconventional superconductivity in topological superconductor candidate YPtBi revealed by ${}^{195}$Pt-NMR
• Intrinsic finite-energy Cooper pairing in $j=3/2$ superconductors
• Nature of the mixed-parity pairing of attractive fermions with spin-orbit coupling in optical lattice
• Proximity effect of time-reversal symmetry broken non-centrosymmetric superconductors
• Effects of spin orbit coupling on proximity induced superconductivity
• Strong-coupling superconductivity of the Heusler-type compound ScAu2Al: Ab-initio studies
• Helical Topological Superconducting Pairing at Finite Excitation Energies
• Anomalous magnetotransport in the single-crystalline half-Heusler antiferromagnet ErPdSb
• Thermodynamic and electrical transport properties of the half-Heusler plumbide TbAuPb
• Quantum Oscillations and Superconductivity in YPtBi Under Pressure
• Determination of the London penetration depth with the tunnel diode oscillator technique