Revealing the Hidden Heavy Fermi Liquid in CaRuO3

Abstract

The perovskite ruthenate has attracted considerable interest due to reports of possible non-Fermi-liquid behavior and its proximity to a magnetic quantum critical point, yet its ground state and electronic structure remain enigmatic. Here we report the first measurements of the Fermi surface and quasiparticle dispersion in CaRuO3 through a combination of oxide molecular beam epitaxy and in situ angle-resolved photoemission spectroscopy. Our results reveal a complex and anisotropic Fermi surface consisting of small electron pockets and straight segments, consistent with the bulk orthorhombic crystal structure with large octahedral rotations. We observe a strongly band-dependent mass renormalization, with prominent heavy quasiparticle bands which lie close to the Fermi energy and exhibit strong temperature dependence. These results are consistent with a heavy Fermi liquid with a complex Fermiology and small hybridization gaps near the Fermi energy. Our results provide a unified framework for explaining previous experimental results on CaRuO3, such as its unusual optical conductivity, and demonstrate the importance of octahedral rotations in determining the quasiparticle band structure, and electron correlations in complex transition metal oxides.

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References in corpus (6)

• Strong electronic correlations from Hund's coupling
• The coherence-incoherence crossover and the mass-renormalization puzzles in Sr2RuO4
• How bad metals turn good: spectroscopic signatures of resilient quasiparticles
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• Electronic correlations, magnetism and Hund's rule coupling in the ruthenium perovskites SrRuO${}_3$ and CaRuO${}_3$

Cited by in corpus (1)

• Hall coefficient signals orbital differentiation in the Hund's metal Sr${}_2$RuO${}_4$