On the 5f electronic ground state in UGe2 at ambient pressure

We report x-ray absorption and magnetic circular dichroism measurements performed at the M4,5 edges of uranium in the ferromagnetic superconductor UGe2. The spectra are described with the LSDA + U electronic structure computation method. Combined with the analysis of the published (i) x-ray photoemission spectrum, (ii) electron-positron momentum density, and (iii) angular dependence of the de Haas-van Alphen frequencies, we infer for the Coulomb repulsion energy within the 5f electron shell U less than or similar to 2 eV. This leads to U/W similar or equal to 2 where W is the bandwidth.