Distinct Uniaxial Stress and Pressure Fingerprint of Superconductivity in the 3D Kagome Lattice Compound CeRu2

TL;DR

This study investigates how uniaxial stress and hydrostatic pressure differently influence the superconducting properties of the 3D Kagome lattice compound CeRu2, revealing tunable pairing symmetry and superfluid density behavior.

Contribution

It provides the first detailed comparison of uniaxial stress and hydrostatic pressure effects on superconductivity in CeRu2, highlighting their distinct impacts on pairing symmetry and superfluid density.

Findings

Uniaxial stress induces a dome-shaped $T_c$ evolution and changes pairing symmetry.

Hydrostatic pressure maintains $T_c$ but alters superfluid density to nodal behavior.

CeRu2 shows highly responsive and multifold tunability of superconductivity.

Abstract

The exploration of tunable superconductivity in strongly correlated electron systems is a central pursuit in condensed matter physics, with implications for both fundamental understanding and potential applications. The Laves phase CeRu$_{2}$, a pyrochlore compound, exhibits a three-dimensional (3D) Kagome lattice type geometry giving rise to flat bands and degenerate Dirac points, where band structure features intertwine with strong multi-orbital interaction effects deriving from its correlated electronic structure. Here, we combine muon spin rotation ($\mu$SR), uniaxial in-plane stress, and hydrostatic pressure to probe the superconducting state of CeRu$_{2}$. Uniaxial stress up to 0.22 GPa induces a dome-shaped evolution of the critical temperature $T_{\rm c}$, with an initial plateau, successively followed by enhancement and suppression without any structural phase transition. Stress is further found to drive a crossover from anisotropic to isotropic $s$-wave pairing. In contrast, hydrostatic pressure up to 2.2 GPa leaves $T_{\rm c}$ largely unchanged but alters the superfluid density from exponential to linear behavior at low temperatures, indicative of nodal superconductivity under hydrostatic pressure. Taken together, these results indicate that CeRu$_{2}$ occupies an ideal position in parameter space, enabling highly responsive and multifold tunability of superconductivity in this three-dimensional correlated electronic system. This warrants further quantitative analysis of the interplay between lattice geometry, electronic correlations, and pairing symmetry.