Formation of the coherent heavy fermion liquid at the 'hidden order' transition in URu2Si2

TL;DR

This study uses high-resolution ARPES to investigate the electronic structure of URu2Si2, revealing the formation of a coherent heavy fermion liquid during the hidden order transition.

Contribution

It provides direct spectroscopic evidence of the evolution from weakly dispersive states to a coherent heavy fermion liquid at the hidden order transition in URu2Si2.

Findings

Existence of weakly dispersive states above the transition

Transformation into a coherent heavy fermion liquid below the transition

Hybridization of heavy fermion states with conduction bands

Abstract

In this article we present high-resolution angle-resolved photoemission (ARPES) spectra of the heavy-fermion superconductor URu$_2$Si$_2$. Measurements as a function of both excitation energy and temperature allow us to disentangle a variety of spectral features, revealing the evolution of the low energy electronic structure across the hidden order transition. Already above the hidden order transition our measurements reveal the existence of weakly dispersive states below the Fermi level that exhibit a large scattering rate. Upon entering the hidden order phase, these states transform into a coherent heavy fermion liquid that hybridizes with the conduction bands.