Stabilization of U 5f2 configuration in UTe2 through U 6d dimers in the presence of Te2 chains

Abstract

We investigate the topological superconductor candidate ${\mathrm{UTe}}_2$ using high-resolution valence-band resonant inelastic x-ray scattering at the U $M_{4,5}$ edges. We observe atomiclike low-energy excitations that support the correlated nature of this unconventional superconductor. These excitations originate from the U $5f^2$ configuration, which is unexpected since the short Te2-Te2 distances exclude Te2 being $2-$. By utilizing the photoionization cross-section dependence of the photoemission spectra in combination with band structure calculations, we infer that the stabilization of the U $5f^2$ configuration is due to the U $6d$ bonding states in the U dimers acting as a charge reservoir. Our results emphasize that the description of the physical properties should commence with a $5f^2$ ansatz.