Electronic Structure Study of a Kondo Lattice System CeCuSb₂

 Investigating the electronic structure of a rare-earth-based system has various complexity due to the correlation of f electrons [1]. In the rare earth series, Ce has some unique properties due to the higher radial expansion of f orbital. We have studied the electronic structure of CeCuSb₂, which is an antiferromagnetic Kondo lattice system [2] and forms in layered tetragonal structure. We performed high-resolution hard x-ray photoemission spectroscopy of a CeCuSb₂ single crystal by varying photon energy and temperature. We observed that the surface termination affects the hybridization of Ce atoms. Though the bulk studies show Kondo behavior, the Ce 3d core-level spectra do not show the temperature dependence of the features expected in a Kondo lattice system. Sb spectra at different photon energies show significant differences with the change in surface sensitivity manifesting surface-bulk difference in the electronic structure. Sb(2) is found to be relatively more strongly bonded to Ce than Sb(1); the differences reduce at higher temperatures. These results provide an interesting scenario of the evolution of complex hybridization physics and their surface-bulk differences.