Superconducting state in YSn3 with a AuCu3-type structure

In this paper, the superconducting properties of ${\text{YSn}}_{3}$ are reported. ${\text{YSn}}_{3}$ has a cubic ${\text{AuCu}}_{3}$-type structure with the space group $Pm\overline{3}m$. Magnetic susceptibility, electrical resistivity, and specific-heat data showed that ${\text{YSn}}_{3}$ is a superconductor with a superconducting transition temperature $({T}_{\text{c}})$ of 7 K. The magnetization versus magnetic field $(M\text{\ensuremath{-}}H)$ curve shows the typical type-II superconducting behavior. The estimated lower critical field ${H}_{\text{c}1}(0)$ and the upper critical field ${H}_{\text{c}2}(0)$ are about 90 Oe and 3000 Oe, respectively. The penetration depth $\ensuremath{\lambda}(0)$ and coherence length $\ensuremath{\xi}(0)$ are calculated to be approximately 270 nm and 66 nm, respectively, using the Ginzburg-Landau equations. The estimated Sommerfeld coefficient ${\ensuremath{\gamma}}_{\text{N}}$ is $7.57\text{ }\text{mJ}/\text{mol}\text{ }{\text{K}}^{2}$. The normalized specific heat jump $\ensuremath{\Delta}C/{\ensuremath{\gamma}}_{\text{N}}{T}_{\text{c}}$ is estimated to be about 2.19, which is higher than the value predicted by the BCS theory in the weak-coupling limit, i.e., $\ensuremath{\Delta}C/{\ensuremath{\gamma}}_{\text{N}}{T}_{\text{c}}=1.43$. This fact indicates that superconductivity in ${\text{YSn}}_{3}$ exists in the strong-coupling regime. The difference between ${T}_{\text{c}}$ of $\text{Ln}{X}_{3}$ ($X=\text{family}$ of 13 or 14 elements) compounds is discussed to compare their physical properties.