We report a detailed calorimetric study on single crystals of the 5$d$-transition metal pnictide SrPt${}_2$As${}_2$ with a superconducting critical temperature $T_c\sim 5$ K. The peculiar field dependence of the electronic specific heat coefficient $\gamma$ can be decomposed into two linear components. Moreover, the temperature evolution of the electronic specific heat below $T_c$ is best described by a two-gap model. These findings suggest that two energy gaps are associated with the superconductivity. In parallel, we show that the spin-lattice relaxation time $T_1$, through nuclear magnetic resonance measurement, obeys the so-called Korringa relation well. This, along with the $T^2$ dependence of resistivity at low temperatures, points to a Fermi liquid ground state in this material.

• Received 27 March 2013

DOI:https://doi.org/10.1103/PhysRevB.87.224507