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

Department of Condensed Matter Physics and Materials' Science, Tata Institute of Fundamental Research Homi Bhabha Road, Colaba, Mumbai 400005, India

^(a) kbmaiti@tifr.res.in (corresponding author)

Received: 17 June 2014
Accepted: 29 October 2014

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.