Superconducting properties of Ta₃Sb and Ti₃Sb, A15 compounds which are candidate topological superconductors

We present a study of the superconducting properties of polycrystalline Ti₃Sb (T_c ~ 5.9 K) and Ta₃Sb (T_c ~ 0.67 K), candidate topological superconductors of the A15 family. Via magneto-transport, magnetization and calorimetry measurements, we determine the superconducting phase diagram for both compounds and find large Ginsburg-Landau parameters for both Ti₃Sb (κ = 55) and Ta₃Sb (κ = 90) , identifying them as extremely type-II superconductors. Calorimetry and London penetration depth measurements at ³He temperatures are consistent with a full BCS-like superconducting gap in both compounds.