Disorder-sensitive superconductivity in the iron silicide Lu$_2$Fe$_3$Si$_5$ studied by the Lu-site substitutions

TL;DR

This study investigates how impurities affect superconductivity in Lu$_2$Fe$_3$Si$_5$, revealing disorder-sensitive pairing and evidence for sign reversal of the order parameter through impurity-induced $T_c$ suppression.

Contribution

It demonstrates the impact of both magnetic and non-magnetic impurities on superconductivity and provides evidence for sign-changing pairing in Lu$_2$Fe$_3$Si$_5$.

Findings

Non-magnetic impurities rapidly suppress $T_c$.

Superconductivity is strongly affected by disorder.

Evidence for sign reversal of the order parameter.

Abstract

We studied effect of non-magnetic and magnetic impurities on superconductivity in Lu$_2$Fe$_3$Si$_5$ by small amount substitution of the Lu site, which investigated structural, magnetic, and electrical properties of non-magnetic (Lu$_{1-x}$Sc$_x$)$_2$Fe$_3$Si$_5$, (Lu$_{1-x}$Y$_x$)$_2$Fe$_3$Si$_5$, and magnetic (Lu$_{1-x}$Dy$_x$)$_2$Fe$_3$Si$_5$. The rapid depression of $T_c$ by non-magnetic impurities in accordance with the increase of residual resistivity reveals the strong pair breaking dominated by disorder. We provide compelling evidence for the sign reversal of the superconducting order parameter in Lu$_2$Fe$_3$Si$_5$.