We measured the ultra-low-temperature specific heat and thermal conductivity of Au2Pb single crystal, a possible three-dimensional Dirac semimetal with a superconducting transition temperature Tc≈ 1.05 K. The electronic specific heat can be fitted by a two-band s-wave model, which gives the gap amplitudes Δ1(0)/kBTc = 1.38 and Δ2(0)/kBTc = 5.25. From the thermal conductivity measurements, a negligible residual linear term κ0/T in zero field and a slow field dependence of κ0/T at low field are obtained. These results suggest that Au2Pb has a fully gapped superconducting state in the bulk, which is a necessary condition for topological superconductor if Au2Pb is indeed one.
@article{arxiv.1609.06186,
title = {Fully gapped superconducting state in Au2Pb: a natural candidate for topological superconductor},
author = {Y. J. Yu and Y. Xu and Y. Xing and J. Zhang and T. P. Ying and X. C. Hong and M. X. Wang and X. Zhang and S. Jia and J. Wang and S. Y. Li},
journal= {arXiv preprint arXiv:1609.06186},
year = {2017}
}