Direct Observation of Pressure-induced Yb Valence Transition in YbInCu4

Abstract

The Yb valence state of YbInCu4 was measured at 300 and 13 K under pressure by high-resolution x-ray absorption spectroscopy (XAS). The electronic structure of Cu was also measured by XAS at the Cu-K absorption edge. Pressure-induced disappearance of the valence transition was observed directly at 13 K. The present results suggest a charge transfer from Yb to Cu sites at 13 K after the disappearance of the valence transition under pressure.