Electronic correlations are dominated by c−f hybridization in the pyrochlore superconductor CeRu2

Abstract

Flat bands near the Fermi energy (EF) enhance the density of states and promote strong electronic correlations, often driving novel quantum phases. Understanding the microscopic origin of these correlations is essential for uncovering the mechanisms behind correlated phenomena such as superconductivity and magnetism. Here, we investigate the electronic structure of the three-dimensional pyrochlore superconductor CeRu2 using angle-resolved photoemission spectroscopy. The Ru sublattice forms a three-dimensional kagome network, theoretically predicted to host flat bands. While we resolve dispersive Ru 4d–derived bands near EF, their high band velocities suggest a minimal contribution to low-energy correlations. In contrast, we observed clear signatures of strong hybridization between Ce 4f and Ru 4d states at EF. Our results identify Ce 4f electrons as the primary source of strong correlations in CeRu2, providing crucial insight into the microscopic origin of its superconductivity and magnetic phenomena.

Source-reported materials — not catalogue approval

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