Fermi surface variation of Ce 4f-electrons in hybridization controlled heavy-fermion systems.

Ce 3 d –4 f resonant angle-resolved photoemission measurements on CeCoGe 1.2 Si 0.8 and CeCoSi 2 have been performed to understand the Fermi surface topology as a function of hybridization strength between Ce 4 f - and conduction electrons in heavy-fermion systems. We directly observe that the hole-like Ce 4 f -Fermi surfaces of CeCoSi 2 is smaller than that of CeCoGe 1.2 Si 0.8 , indicating the evolution of the Ce 4 f -Fermi surface with the increase of the hybridization strength. In comparison with LDA calculation, the Fermi surface variation cannot be understood even though the overall electronic structure is roughly explained, indicating the importance of strong correlation effects. [ABSTRACT FROM AUTHOR]