Measurements of Superconducting Properties in the Non-Centrosymmetric Superconductor AuPb₃

Non-centrosymmetric superconductors lack inversion symmetry in their crystal structure which induces Rashba–like antisymmetric spin-orbit coupling, lifting spin degeneracy of electrons. Theory predicts an admixture of spin-singlet and spin-triplet symmetry for the superconducting states. AuPb₃ crystallizes in a non-centrosymmetric tetragonal structure (space group 121) and has a superconducting transition temperature ~ 4.4 K. We synthesized polycrystalline AuPb₃ and performed magnetization, specific heat, and electrical resistivity measurements down to 100 mK. Magnetization measured in field-cooled and zero-field-cooled samples shows AuPb₃ is a Type II superconductor. The electronic heat capacity below the transition temperature shows power law rather than exponential behavior, which is consistent with non-BCS superconductivity. Broadening of the resistivity and specific heat curves with field also indicates unusual behavior that needs further investigation.