paper

Fully gapped superconductivity in Ni-pnictide superconductors BaNi2As2 and SrNi2P2

arXiv:1102.0834 · doi:10.1088/1742-6596/273/1/012097

Abstract

We have performed low-temperature specific heat $C$ and thermal conductivity $I^º$ measurements on the Ni-pnictide superconductors BaNi $_{2}$ As $_{2}$ ( $T_{c}$ =0.7 K and SrNi $_{2}$ P $_{2}$ ( $T_{c}$ =1.4 K). The temperature dependences $C (T)$ and $I^º (T)$ of the two compounds are similar to the results of a number of s-wave superconductors. Furthermore, the concave field responses of the residual $I^º$ for BaNi $_{2}$ As $_{2}$ rules out the presence of nodes on the Fermi surfaces. We postulate that fully gapped superconductivity could be universal for Ni-pnictide superconductors. Specific heat data on Ba $_{0.6}$ La $_{0.4}$ Ni $_{2}$ As $_{2}$ shows a mild suppression of $T_{c}$ and $H_{c2}$ relative to BaNi $_{2}$ As $_{2}$ .

5 pages, 3 figures, to be published in J. Phys.: Conf. Ser