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  eV. This leads to where W is the bandwidth.