Soft x-ray magnetic circular dichroism study on UGe2

In order to investigate the electronic and magnetic states of UGe2 element-specifically, we have performed soft x-ray magnetic circular dichroism experiments at the U N4,5 and Ge L2,3 absorption edges. We have detected the XMCD signals at both the U and Ge sites and observed clear hysteresis loops in the ferromagnetic (FM) state at T = 5.5 K. From the branching ratio B, it is found that the occupation number of 5f electrons (n5f) in UGe2 is close to 3. In addition, applying the magneto-optical sum rules analysis to the XMCD spectrum at the U N4,5 edges, the ratio of orbital magnetic moment to the spin magnetic moment (-ML/MS) is estimated to be 2.17. These values of B and -ML/MS are comparable compared with the results of other FM superconductors: URhGe and UCoGe.