Obstacles to superconductivity in CsCl phases

Superconductivity in Heusler compound ScAu2Al

We report superconducting state properties and electronic structure of a full Heusler material ScAu₂Al. 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 highestT_c-regime among the Heusler superconductors. The magnetization data shows that ScAu₂Al 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 ScAu₂Al. 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 ScAu₂Al. Further, we show that the observedλ_e-phvalue in ScAu₂Al is the highest amongst the reported Heusler superconductors, indicating strong correlation betweenT_candλ_e-phvalues 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 ScAu₂Al.