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

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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 Tc, 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 Tc 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.
Funding Information
  • Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung (TMSGI2_211750)

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