Photoemission measurements of EuB6

We have measured the UPS(He II) and XPS(MgKα) of the valence band of EuB6 in order to determine possible mixing of trivalent Eu3+ states with the dominant divalent states. As a result, the mixed valence was not found within the experimental error. Aside from the mixed-valence problem, it became clear that the shape and position of Eu2+ 4f band in UPS can not be fully explained by the multiplet terms of the final state. It is suggested that the shape and position shift of the 4f band in UPS(He II) might be explained mainly by the self-energy part in the electron-electron interactions between initial- and final-propagators in the many body descriptions of the photoemission process. (author)