Stabilization of U 5f^{2} configuration in UTe_{2} through U 6d dimers in the presence of Te2 chains

Abstract

We investigate the topological superconductor candidate 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.