Imaging the formation of high-energy dispersion anomalies in the actinide UCoGa$_5$

TL;DR

This study uses ARPES to reveal high-energy dispersion anomalies in UCoGa$_5$, linking them to spin fluctuations and challenging the conventional Fermi liquid description of this actinide compound.

Contribution

It demonstrates that dispersion anomalies in UCoGa$_5$ are caused by spin fluctuations, providing new insights into electronic interactions in actinides.

Findings

Detection of dispersion kinks at 130 meV and 1 eV

Anomalies are explained by coupling to spin fluctuations

Resemblance to high-temperature superconductor phenomena

Abstract

We use angle-resolved photoemission spectroscopy (ARPES) to image the emergence of substaintial dispersion anomalies in the electronic renormalization of the actinide compound UCoGa$_5$ which was presumed to belong to a conventional Fermi liquid family. Kinks or abrupt breaks in the slope of the quasiparticle dispersion are detected both at low ($\sim$130 meV) and high ($\sim$1 eV) binding energies below the Fermi energy, ruling out any significant contribution of phonons. We perform numerical calculations to demonstrate that the anomalies are adequately described by coupling between itinerant fermions and spin fluctuations arising from the particle-hole continuum of the spin-orbit split $5f$ states of uranium. These anomalies are resemble the `waterfall' phenomenon of the high-temperature copper-oxide superconductors, suggesting that spin fluctuations are a generic route toward multiform electronic phases in correlated materials as different as high-temperature superconductors and actinides.