| Using high-resolution angle-resolved photoemission we studied ordered Cerium surface alloys on Pt(111) and Ag(111) surfaces. We present light polarization dependent bandstructure and Fermi surfaces for several photon energies including Ce 4d-4f resonant photoemission. In the CePt5 surface alloy, we show the temperature dependence of the Cerium 4f electron spectral weight near the Fermi level. There we observed the opening of a hybridisation gap between the flat 4f Cerium band and one strongly dispersing Pt conduction band that has a strong temperature dependence. The comparison to LDA+DMFT calculations based on an NCA solver shows the on-set of the coherent heavy fermion state at low temperature below the Kondo temperature of the material. |
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