Superconducting properties and gap structure of the topological superconductor candidate Ti3Sb

Abstract

We present a study of the superconducting properties of the candidate topological superconductor Ti3Sb. Electrical transport measurements show zero resistance with a Tc,onset of ≈5.9 K with a transition width ΔTc≈0.6 K. The superconducting phase boundaries as derived from magnetotransport and magnetic susceptibility measurements agree well. We estimate an upper critical field Bc2(0)≈4.5 T. A Ginzburg-Landau (GL) analysis yields values of the coherence length and penetration depth of ξ=6.2 nm and λ=340 nm, respectively, and a GL parameter κ≈55, indicating extreme type-II behavior. Furthermore, we observe a step height in the specific heat ΔCeγTc≈1.61±0.24 (with Tc=4.8±0.4 K), a value larger than the Bardeen-Cooper-Schrieffer value of 1.43, suggesting modest coupling. Measurements of the temperature dependence of the London penetration depth via the tunnel-diode oscillator technique down to ≈450 mK show a full superconducting gap, consistent with a conventional s-wave gap structure.

Source-reported materials — not catalogue approval

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