On the $^{12}$C/$^{13}$C carbon isotope effect in the quasi one-dimensional superconductor Sc$_3$CoC$_4$

TL;DR

This study investigates the isotope effect in the quasi-one-dimensional superconductor Sc$_3$CoC$_4$, finding results consistent with BCS theory, and uses isotope substitution to explore superconductivity mechanisms in this class of materials.

Contribution

It provides the first systematic analysis of the carbon isotope effect in Sc$_3$CoC$_4$, establishing its alignment with BCS theory predictions.

Findings

Isotope coefficient close to 0.58, near BCS value of 0.5.

Homogeneity confirmed by X-ray diffraction and NMR.

Supports phonon-mediated superconductivity in this material.

Abstract

Sc$_3$CoC$_4$ is the only superconductor in the group of the isotypic carbides Sc$_3M$C$_4$ ($M$ = Mn, Fe, Ru, Os, Co, Rh, Ir, Ni), rendering it into an ideal benchmark system to systematically study the prerequisites and mechanism of superconductivity in such quasi one-dimensional structures. To investigate the isotope effect, the substitution series Sc$_3$Co($^{12}$C$_{1-x}$$^{13}$C$_x$)$_4$ with $x$ = 0, 0.5 and 1 was synthesized by arc melting. The sample homogeneity was confirmed by powder X-ray diffraction and NMR spectroscopy. The resulting isotope coefficient based on magnetization studies on polycrystalline samples and electrical resistivity measurements on single crystals of $\alpha$ = 0.58 lies close to the value of 0.5 predicted by BCS theory.