Regensburg 2019 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 52: Quantum Impurities and Kondo Physics

TT 52.7: Vortrag

Donnerstag, 4. April 2019, 11:00–11:15, H7

Heavy quasiparticle bands in the underscreened quasiquartet Kondo lattice — •Alireza Akbari¹ and Peter Thalmeier² — ¹Asia Pacific Center for Theoretical Physics, POSTECH, Pohang, Korea — ²Max Planck Institute for Chemical Physics of Solids, Dresden, Germany

We study the quasiparticle spectrum in an underscreened Kondo-lattice (KL) model that involves a single spin degenerate conduction band and two crystalline-electric-field (CEF) split Kramers doublets coupled by both orbital-diagonal and non-diagonal exchange interactions. We find the three quasiparticle bands of the model using a constrained fermionic mean field approach. While two bands are similar to the one-orbital model a new genuinely heavy band inside the main hybridization gap appears in the quasiquartet model. Its dispersion is due to effective hybridization with conduction states but the bandwidth is controled by the size of the CEF splitting. Furthermore several new indirect and direct hybridztion gaps may be identified. By solving the selfconsistency equation we calculate the CEF-splitting and exchange dependence of effective Kondo low energy scale, hybridization gaps and band widths. We also derive the quasiparticle spectral densities and their partial orbital contributions. We suggest that the two-orbital KL model can exhibit mixed CEF/Kondo excitonic magnetism.
Phys. Rev. B 98, 155121 (2018)