Superconductivity in Heusler compound ScAu 2 Al.

We report superconducting state properties and electronic structure of a full Heusler material ScAu 2 Al. The resistivity measurement indicates a zero-field (at nominal Earth's field) superconducting transition temperature, T c = 5.12 K (in contrary to the previously reported value of 4.4 K), which falls in the highest T c -regime among the Heusler superconductors. The magnetization data shows that ScAu 2 Al is a moderate type-II superconductor, where the critical field values can be estimated from the Ginzburg-Landau-Abrikosov-Gorkov theory. The field-dependent magnetization response further shows signatures of flux jump in ScAu 2 Al. A sharp jump in the temperature dependent specific heat ( C p ) data confirms bulk superconductivity. We report that the electron-phonon coupling constant, λ e-ph = 0.77, suggesting a moderate electron-phonon coupling in ScAu 2 Al. Further, we show that the observed λ e-ph value in ScAu 2 Al is the highest amongst the reported Heusler superconductors, indicating strong correlation between T c and λ e-ph values and significant role of electron-phonon coupling in mediating superconductivity in Heusler superconductors. Finally, we discuss the electronic properties and reveal the existence of van Hove singularity near the Fermi level in ScAu 2 Al.