Importance of conduction electron correlation in a Kondo lattice,Ce2CoSi3

Abstract

Kondo systems are usually described by the interaction of the correlation induced localmoments with the highly itinerant conduction electrons. Here, we study the role of electroncorrelations among conduction electrons in the electronic structure of a Kondo lattice compound,Ce2CoSi3, using high resolution photoemission spectroscopy and ab initio band structurecalculations, where Co 3d electrons contribute in the conduction band. High energyresolution employed in the measurements helped to reveal the signatures of Ce 4fstates derived Kondo resonance features at the Fermi level and the dominanceof Co 3d contributions at higher binding energies in the conduction band. Thelineshape of the experimental Co 3d band is found to be significantly differentfrom that obtained from the band structure calculations within the local densityapproximations, LDA. Consideration of electron–electron Coulomb repulsion,U, among Co 3delectrons within the LDA + U method leads to a better representation of experimental results. The signature of anelectron correlation induced satellite feature is also observed in the Co 2p core levelspectrum. These results clearly demonstrate the importance of the electron correlationamong conduction electrons in deriving the microscopic description of such Kondosystems.