Superconducting properties of the spin Hall candidate Ta3Sb with eightfold degeneracy

Abstract

We report the synthesis and characterization of phase pure Ta3Sb, a material predicted to be topological with eightfold degenerate fermionic states [Science 353, aaf5037 (2016)] and to exhibit a large spin Hall effect [Sci. Adv. 5, eaav8575 (2019]. We observe superconductivity in Ta3Sb with Tc~ 0.67 K in both electrical resistivity \r{ho}(T) and specific heat C(T) measurements. Field dependent measurements yield the superconducting phase diagram with an upper critical field of Hc2(0) ~ 0.95 T, corresponding to a superconducting coherence length of ξ ~18.6 nm. The gap ratio deduced from specific heat anomaly, 2Δ0/kBTc is 3.46, a value close to the Bardeen-Cooper-Schrieffer (BCS) value of 3.53. From a detailed analysis of both the transport and thermodynamic data within the Ginsburg-Landau (GL) framework, a GL parameter of \k{appa} ~90 is obtained identifying Ta3Sb as an extreme type-II superconductor. The observation of superconductivity in an eightfold degenerate fermionic compound with topological surface states and predicted large spin Hall conductance positions Ta3Sb as an appealing platform to further explore exotic quantum states in multifold degenerate systems.

16 Pages, 3 figures

References in corpus (8)

• Signatures of Majorana fermions in hybrid superconductor-semiconductor nanowire devices
• Superconductivity in the A15 Structure
• Nematic superconductivity in doped Bi2Se3 topological superconductors
• Membrane-based nanocalorimeter for high-resolution measurements of low-temperature specific heat
• Fermions and bosons in nonsymmorphic PdSb2 with sixfold degeneracy
• Observation of sixfold degenerate fermions in PdSb${}_2$
• Study of the superconducting ground state of topological superconducting candidates Ti${}_3$X (X = Ir, Sb)
• Triple point fermions in ferroelectric GeTe

Cited by in corpus (4)

• Realization of Practical Eightfold Fermions and Fourfold van Hove Singularity in TaCo${}_2$Te${}_2$
• Dirac surface states, multiorbital dimerization and superconductivity in Nb- and Ta-based A15 compounds
• Superconducting properties and gap structure of the topological superconductor candidate Ti_(3)Sb
• A15 Phase Ta3Sb Thin Films: Direct Synthesis, Charge Transport and Spin-Orbit Torque