Importance of Co 3d electron correlation in a Ce-based Kondo lattice, Ce(2)CoSi(3)

TL;DR

This study highlights the crucial role of electron correlations among Co 3d electrons in Ce2CoSi3, showing that including Coulomb repulsion improves the understanding of its electronic structure and Kondo behavior.

Contribution

The paper demonstrates that considering electron-electron Coulomb repulsion among Co 3d electrons is essential for accurately modeling the electronic structure of Ce2CoSi3.

Findings

Identification of Ce 4f Kondo resonance at the Fermi level

Significant difference between experimental and LDA band shapes

Correlation strength among Co 3d electrons is about 3 eV

Abstract

We study the role of electron correlations among Co 3d electrons contributing to the conduction band of a Kondo lattice compound, Ce2CoSi3, using high resolution photoemission spectroscopy and ab initio band structure calculations. Experimental results reveal signature of Ce 4$f$ states derived Kondo resonance feature at the Fermi level and dominance of Co 3d contributions at higher binding energies in the valence band. The line shape of the experimental Co 3$d$ band is found to be significantly different from that obtained from the band structure calculations within the local density approximations. Consideration of electron-electron Coulomb repulsion among Co 3d electrons leads to a better representation of experimental results. The correlation strength among Co 3$d$ electrons is found to be about 3 eV. Signature of electron correlation induced satellite feature is also observed in the Co 2p core level spectrum. Thus, these results demonstrate the importance of the electron correlation among conduction electrons to derive the microscopic description of such Kondo systems.