Giant spectral renormalization and complex hybridization physics in the Kondo lattice system CeCuSb2

Abstract

We investigate the electronic structure of a Kondo lattice system, CeCuSb 2 exhibiting significant mass enhancement and Kondo-type behavior. We observe multiple features in the hard x-ray photoemission spectra of Ce core levels due to strong final-state effects. The depth-resolved data exhibit a significant change in relative intensity of the features with the surface sensitivity of the probe. The extracted surface and bulk spectral functions are different and exhibit a Kondo-like feature at higher binding energies in addition to the well and poorly screened features. The core-level spectra of Sb exhibit huge and complex changes as a function of the surface sensitivity of the technique. The analysis of the experimental data suggests that the two nonequivalent Sb sites possess different electronic structures and in each category, the Sb layers close to the surface are different from the bulk ones. An increase in temperature influences the Ce-Sb hybridization significantly. The plasmon-excitation-induced loss features are also observed in all core-level spectra. All these results reveal the importance of Ce-Sb hybridizations and indicate that the complex renormalization of Ce-Sb hybridization may be the reason for the exotic electronic properties of this system.

Layer-resolved electronic behavior in a Kondo lattice system, CeAgAs2

“…The constituent peaks are shown in the lower panel. The bulk Ce 3d spectrum shown in figure 3(a) resembles well the bulk spectra of the CeCuSb 2 [8]. Considering the binding energies of the peaks [8], the features A 2 -A 5 in 3d 5/2 signal (B 2 -B 5 in 3d 3/2 signal) are attributed to the multiplets of f 1 and f 2 final states.…”

“…The bulk Ce 3d spectrum shown in figure 3(a) resembles well the bulk spectra of the CeCuSb 2 [8]. Considering the binding energies of the peaks [8], the features A 2 -A 5 in 3d 5/2 signal (B 2 -B 5 in 3d 3/2 signal) are attributed to the multiplets of f 1 and f 2 final states. The low energy feature, A 2 (B 2 in 3d 3/2 feature) corresponds to the well screened, f 2 state.…”

“…In addition, there are low energy intense features A 1 and B 1 . Signature of such features are found in some systems [8,34,35], where the hole created in the conduction/ligand bands due to the hopping of an electron to the core hole site, forms a singlet with other holes and/or has highly itinerant character that allows the valence hole to propagate far away from the photoemission site to lower the energy further. The intensity of these features appear to be quite large in this material.…”

“…For the past few years, this group of samples has attracted additional attention involving exotic non-trivial topological states [7]. In this group, the CeTX 2 compounds are of particular interest due to the presence of electron correlation in the electronic structure induced by the Ce 4f states appearing near Fermi level, ϵ F [8][9][10]. These materials crystallize in the tetragonal HfCuSi 2 type structure belonging to the space group, P4/nmm [11,12].…”