UTe; A Narrow-band superconductor

UTe; 狭バンド超伝導体

Sunermann, M.*; 藤森 伸一   ; 他11名*

Sunermann, M.*; Fujimori, Shinichi; 11 of others*

We investigate the nature of the 5 electrons in the unconventional odd-parity superconductor UTe, focusing on the degree of covalency, mixed versus intermediate valence, and dominant electronic configuration. This is achieved using density functional theory (DFT) in combination with dynamical mean-field theory (DMFT) calculations. A key aspect of our approach is the material-specific tuning of the double-counting correction parameter, , within the DFT + DMFT part. This tuning is guided by the energy dependence of photo-ionization cross-sections in valence band photoelectron spectroscopy. The reliability of the parameters is confirmed by the accurate reproduction of the angle-resolved valence-band photoemission spectra and the U,4 core-level data. The DFT + DMFT model reveals that in UTe the average 5 shell filling is close to 2.5 with the 5 configuration being most prevalent. The model further suggests that the 5 electrons form narrow bands and display mixed-valence fluctuation, while coherent valence dynamics arising from hybridization with the conduction bath are also present. Additionally, the significance of the U,6 states in UTe is discussed.