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TT: Fachverband Tiefe Temperaturen
TT 18: f-Electron Systems and Heavy Fermions II
TT 18.1: Talk
Monday, March 12, 2018, 15:00–15:15, H 3005
Thermodynamics of heavy fermions with crystal-field excitations and lattice coherence — •Farzaneh Zamani1, Stefan Kirchner2, and Johann Kroha1,2 — 1Physikalisches Institut and BCTP, Universität Bonn, Germany — 2Center for Correlated Matter, Zhejiang University, Hangzhou, China
Heavy-fermion (HF) compounds exhibit an interplay of various phenomena, including Kondo effect, lattice coherence and crystal-field (CF) splitting. It is crucial to understand the corresponding features in the thermodynamics of heavy-fermion metals, e.g., in order to separate their energy scales from quantum critical scales. However, a complete understanding has been hampered by the fact that the CF-split angular-momentum multiplets of the rare-earth ions induce multiple spectral resonances near the Fermi energy (CF satellites), which are of Kondo-like many-body origin. Thus, not only their occupation number is thermally activated, but also their spectral weight depends on temperature, leading to complex thermodynamic behavior. We clarify the many-body nature of the CF excitations. We develop the Dynamical Mean-Field Theory for the multi-orbital, CF-split Anderson lattice model, using the self-consistent slave particle technique as an impurity solver, accurate down to well below the Kondo scale. We employ a novel gauge fixing technique for fixing the U(1) gauge of the slave particle fields which enables a highly accurate calculation of the free energy and its thermodynamic derivatives. Thermodynamic and spectroscopic results for both, the multi-orbital Anderson lattice and the single-impurity case, are presented.