Identifying f-electron symmetries of UTe2 with O-edge resonant inelastic X-ray scattering

TL;DR

This study uses RIXS and XAS techniques combined with modeling to determine the f-electron configuration in UTe2, providing insights into its electronic structure relevant to its superconductivity.

Contribution

It offers new experimental evidence supporting an 5f^2 6d^1-like valence state in UTe2, clarifying the debate on its electronic configuration and magnetic correlations.

Findings

Data strongly supports 5f^2 6d^1 valence configuration

Weak intra-dimer magnetic correlations observed

Provides context for understanding superconducting pairing mechanism

Abstract

The recent discovery of spin-triplet superconductivity emerging from a non-magnetic parent state in UTe$_2$ has stimulated great interest in the underlying mechanism of Cooper pairing. Experimental characterization of short-range electronic and magnetic correlations is vital to understanding these phenomena. Here we use resonant inelastic X-ray scattering (RIXS), X-ray absorption spectroscopy (XAS), and atomic multiplet-based modeling to shed light on the active debate between 5$f^2$6$d^1$-based models with singlet crystal field states versus 5$f^3$-based models that predict atomic Kramers doublets and much greater 5$f$ itinerancy. The XAS and RIXS data are found to agree strongly with predictions for an 5$f^2$6$d^1$-like valence electron configuration with weak intra-dimer magnetic correlations, and provide new context for interpreting recent investigations of the electronic structure and superconducting pairing mechanism.