Momentum-resolved evolution of the Kondo lattice into 'hidden-order' in URu2Si2

TL;DR

This study uses high-resolution ARPES to investigate how the electronic structure of URu2Si2 evolves from the Kondo regime to the hidden-order state, revealing anisotropic hybridization gaps and momentum-dependent electronic changes.

Contribution

It provides detailed momentum-resolved insights into the evolution of hybridization and electronic structure across the hidden-order transition in URu2Si2.

Findings

Hybridization gap of 11 meV exists above the HO transition.

Hidden order causes anisotropic changes in electronic structure.

Gaps open in momentum space at Gamma and Z points in the HO state.

Abstract

We study, using high-resolution angle-resolved photoemission spectroscopy, the evolution of the electronic structure in URu2Si2 at the Gamma, Z and X high-symmetry points from the high-temperature Kondo-screened regime to the low-temperature `hidden-order' (HO) state. At all temperatures and symmetry points, we find structures resulting from the interaction between heavy and light bands, related to the Kondo lattice formation. At the X point, we directly measure a hybridization gap of 11 meV already open at temperatures above the ordered phase. Strikingly, we find that while the HO induces pronounced changes at Gamma and Z, the hybridization gap at X does not change, indicating that the hidden-order parameter is anisotropic. Furthermore, at the Gamma and Z points, we observe the opening of a gap in momentum in the HO state, and show that the associated electronic structure results from the hybridization of a light electron band with the Kondo-lattice bands characterizing the paramagnetic state.