Distinct uniaxial stress and pressure fingerprint of superconductivity in the 3D kagome lattice compound CeRu2.

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 CeRu₂, 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 (μSR), uniaxial in-plane stress, and hydrostatic pressure to probe the superconducting state of CeRu₂. Uniaxial stress up to 0.22 GPa induces a dome-shaped evolution of the critical temperature T _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 1.9 GPa leaves T _c largely unchanged but alters the superfluid density from exponential to linear behavior at low temperatures, indicative of nodal superconductivity under hydrostatic pressure. These findings identify CeRu₂ as a prime platform for multifold tuning of superconductivity in a 3D correlated material.