How strongly correlated is MnSi

We present an experimental study of the electronic structure of MnSi. Using X-ray Absorption Spectroscopy, X-ray photoemission and X-ray fluorescence we provide experimental evidence that MnSi has a mixed valence ground state. We show that self consistent LDA supercell calculations cannot replicate the XAS spectra of MnSi, while a good match is achieved within the atomic multiplet theory assuming a mixed valence ground state. We discuss the role of the electron-electron interactions in this compound and estimate that the valence fluctuations are suppressed by a factor of 2.5, which means that the Coulomb repulsion is not negligible.