Importance of conduction electron correlation in a Kondo lattice, Ce₂CoSi₃

Abstract

Kondo systems are usually described by the interaction of the correlation induced local moments with the highly itinerant conduction electrons. Here, we study the role of electron correlations among conduction electrons in the electronic structure of a Kondo lattice compound, Ce₂CoSi₃, using high resolution photoemission spectroscopy and ab initio band structure calculations, where Co 3d electrons contribute in the conduction band. High energy resolution employed in the measurements helped to reveal the signatures of Ce 4f states derived Kondo resonance features at the Fermi level and the dominance of Co 3d contributions at higher binding energies in the conduction band. The lineshape of the experimental Co 3d band is found to be significantly different from that obtained from the band structure calculations within the local density approximations, LDA. Consideration of electron-electron Coulomb repulsion, U, among Co 3d electrons within the LDA + U method leads to a better representation of experimental results. The signature of an electron correlation induced satellite feature is also observed in the Co 2p core level spectrum. These results clearly demonstrate the importance of the electron correlation among conduction electrons in deriving the microscopic description of such Kondo systems.

X-ray photoemission spectrum, electronic structure, and magnetism of UCu2Si2

“…However, the width (at half intensity) of the experimental photoemission peak is larger by about 0.4 eV than the calculated one, nearly independent of U. Similar approach was made in the case of Ce 2 CoSi 3 [41], where different parameters U were used for Ce(4f) and Co(3d) electrons.…”

Evolution of the Kondo resonance feature and its relationship to spin-orbit coupling across the quantum critical point in Ce 2 Rh 1−x Co x Si 3

“…[6][7][8] The valence band consists of Si 3p, Co 3d and Rh 4d electronic states. 9,10 Since the binding energy of the 4d electronic states is higher than the 3d electronic states and 3d electrons are relatively more correlated due to smaller radial extension, 11,12 the substitution of Co at Rh sites influences the effective d-p hybridization as well as the itineracy of the conduction electrons that leads to a plethora of interesting properties. For example, one of the end members, Ce 2 RhSi 3 exhibit antiferromagnetic ordering at about 7 K. studies involving lattice compression/expansion via external pressure or chemical substitutions suggested that this compound lies close to the peak of Doniachs magnetic phase diagram.…”

Electronic structure of Fe-based superconductors

“…A Kondo resonance feature called coherent feature appears at the Fermi level representing the itinerant electrons. The decrease in temperature leads to an increase in the coherent feature intensity at the cost of incoherent features [31,32]. While such increase in spectral intensity can have other origin, it is strongly felt [33] that the enhancement of the feature A with the decrease in temperature shown in figure 1c can be attributed to correlation-induced effects as justified later in the text.…”