Weakly coupled type-II superconductivity in LaCoSi2 single crystal

Abstract

We report single crystal growth of LaCoSi${}_2$ and its superconducting properties. From the electrical resistivity measurement, we determined $T_c=1.2$ K and ${\mu }_0{H}_{c2}=0.18T$. From the specific heat measurement, we estimated the superconducting gap ${\Delta }_0=2.07K$ and revealed that the temperature dependence of the specific heat is well explained by the Mühlschlegel’s calculation, indicating that LaCoSi${}_2$ is a weak-coupling BCS superconductor. We also estimated the GL parameter ${\kappa }_{\mathrm{GL}}=9.8$ from the $H-T$ phase diagram and condensation energy. A large ${\kappa }_{\mathrm{GL}}$ indicates that LaCoSi${}_2$ is a type-II superconductor.