Observation of Kondo resonance in rare-earth hexaborides using high resolution photoemission spectroscopy

Abstract

We studied the electronic structure of rare earth hexaborides, CeB₆, PrB₆ and NdB₆ using state-of-the-art high resolution photoemission spectroscopy. CeB₆ is a dense Kondo system. PrB₆ and NdB₆ are antiferromagnetic (Neel temperature ~7 K), known to be stable moment systems and do not exhibit Kondo effect. Photoemission spectra exhibit distinct signature of surface and bulk electronic structures of these compounds. The energy position of the surface feature is not influenced by the 4f density of states. High resolution spectra of CeB₆ reveal multiple Kondo resonance features in the bulk spectra due to various photoemission final states. Interestingly, high resolution photoemission spectra of antiferromagnetic PrB₆ also exhibit a sharp feature at the Fermi level that shows temperature dependence similar to the Kondo resonance features.