paper

Fully gapped superconductivity in SrNi $_{2}$ P $_{2}$

arXiv:1012.1766 · doi:10.1103/PhysRevB.83.094527

Abstract

We investigated the superconducting gap structure of SrNi $_{2}$ P $_{2}$ ( $T_{c}$ =1.4 K) via low-temperature magneto-thermal conductivity $I^º (T, H)$ measurements. Zero field thermal conductivity $I^º$ decreases exponentially $I^º \propto$ exp( $- a T_{c} / T$ ) with $a$ =1.5, in accord with the BCS theory, and rolls over to a phonon-like $I^º \propto T^{3}$ behavior at low temperature, similar to a number of conventional s-wave superconductors. In addition, we observed a "concave" field dependence of the residual linear term $I^º_{0} (H) / T$ . These facts strongly rule out the presence of nodes in the superconducting energy gap of SrNi $_{2}$ P $_{2}$ . Together with a fully gapped Fermi surface in the superconducting state of BaNi $_{2}$ As $_{2}$ ( $T_{c}$ =0.6-0.7 K), demonstrated in our recent work, these results lead us to postulate that fully gapped superconductivity is a universal feature of Ni-based pnictide superconductors.

7 figures, 5 figures, accepted for publication in Physical Review B

Fully gapped superconductivity in SrNi2​P2​

Abstract

Fully gapped superconductivity in SrNi $_{2}$ P $_{2}$