Hybridization Phenomena in Nearly-Half-Filledf-Shell Electron Systems: Photoemission Study ofEuNi2P2

The mixed-valent compound ${\mathrm{EuNi}}_{2}{\mathrm{P}}_{2}$ was studied by photoemission. Observed splittings and dispersions of the Eu $4{f}^{6}$ final state close to energy crossings of the Eu $4f$ and Ni $3d$ states are explained in terms of hybridization by a momentum and energy dependence of the electron hopping matrix element. These data obtained for a system with more than one $4f$ electron (hole) show that dispersions and hybridization gaps related to Kondo and heavy-fermion behavior can be found in other rare-earth-metal compounds apart from Ce and Yb-based ones.