{\mu}SR and NMR study of the superconducting Heusler compound YPd2Sn

We report on muon spin rotation/relaxation and ${}^{119}$Sn nuclear magnetic resonance (NMR) measurements to study the microscopic superconducting and magnetic properties of the Heusler compound with the highest superconducting transition temperature, \ypd\ ($T_c=5.4$ K). Measurements in the vortex state provide the temperature dependence of the effective magnetic penetration depth $\lambda (T)$ and the field dependence of the superconducting gap $\mathrm{\Delta }(0)$. The results are consistent with a very dirty s-wave BCS superconductor with a gap $\mathrm{\Delta }(0)=0.85(3)$ meV, $\lambda (0)=212(1)$ nm, and a Ginzburg-Landau coherence length ${\xi }_{\mathrm{G}\mathrm{L}}(0)\cong 23$ nm. In spite of its very dirty character, the effective density of condensed charge carriers is high compared to the normal state. The \mSR data in a broad range of applied fields are well reproduced by taking into account a field-related reduction of the effective superconducting gap. Zero-field \mSR measurements, sensitive to the possible presence of very small magnetic moments, do not show any indications of magnetism in this compound.