Electronic Structure of a Kondo Lattice System, CeCuAs2

We study the electronic properties of a Ce-based Kondo material, CeCuAs2 employing high-resolution hard x-ray photoemission spectroscopy. The measurements were done with different photon energies to probe the surface-bulk differences of the electronic structure. Experimental results show a significant difference in the hybridization physics for the surface and bulk electronic structures indicating different Ce valency at the surface compared to the bulk. Surface termination appears to play an important role in the correlation physics of this system. In addition, the experimental spectra show loss features due to plasmon excitations. These results bring out the complexity of this novel Kondo lattice system that does not show magnetic order down to the lowest temperature studied and has significantly different surface-bulk properties.