Soft X-ray angle-resolved photoemission study of YbCu2Ge2

Soft X-ray photoemission spectroscopies have been performed on YbCu2Ge2, which is thought to be a Yb divalent system, to investigate its bulk electronic structure including Yb 4f electrons. Small but finite Yb3+ multiplet peaks were found at 6-12 eV in the angle-integrated spectrum, suggesting that it is a valence fluctuation compound. An 'anti-crossing' Yb 4f bands with conduction bands were observed in the angle-resolved spectrum. This is the evidence that the Yb 4f electrons form a band state through the hybridization with Ge 4p and Cu 3d electrons.