Superconducting properties and gap structure of the topological superconductor candidate Ti3Sb

We present a study of the superconducting properties of the candidate topological superconductor Ti3Sb. Electrical transport measurements show zero resistance with a T-c,T-onset of approximate to 5.9 K with a transition width Delta Tc approximate to 0.6 K. The superconducting phase boundaries as derived from magnetotransport and magnetic susceptibility measurements agree well. We estimate an upper critical field B-c2(0) approximate to 4.5 T. A Ginzburg-Landau (GL) analysis yields values of the coherence length and penetration depth of xi = 6.2 nm and lambda = 340 nm, respectively, and a GL parameter kappa approximate to 55, indicating extreme type-II behavior. Furthermore, we observe a step height in the specific heat Delta C-e/gamma T-c approximate to 1.61 +/- 0.24 (with T-c = 4.8 +/- 0.4 K), a value larger than the Bardeen-Cooper-Schrieffer value of gamma Tc 1.43, suggesting modest coupling. Measurements of the temperature dependence of the London penetration depth via the tunnel-diode oscillator technique down to approximate to 450 mK show a full superconducting gap, consistent with a conventional s-wave gap structure.