Superconductivity in Heusler compound ScAu2Al

Abstract

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 highest T 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 observed λ e–ph value in ScAu2Al 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 ScAu2Al.