Anomalies in the electronic structure of a Pauli paramagnet, La2CoSi3 and a Kondo lattice, Ce2CoSi3

Abstract

We study the electronic structure of a Pauli paramagnetic compound, La2CoSi3 using photoemission spectroscopy and ab initio band structure calculations. Experimental valence band spectra exhibit signature of electron correlation-induced feature around 2.5 eV —the correlation strength among Co 3d electrons is estimated to be close to 3 eV. The Co 2p core level spectra also exhibit correlation-induced satellite features consistent with the scenario in the valence band spectra suggesting importance of conduction electron correlation in addition to the local moment in Kondo lattice systems. The La2CoSi3 valence band spectra could be utilized to extract Ce 4f related spectral features and thus provide a good reference to study Kondo lattice systems in this class of materials. Temperature evolution of various core level spectra is found to be complex, revealing deviations from a typical Fermi-liquid behavior and emergence of a distinct surface-bulk difference in the electronic structure at finite temperature.