Berlin 2015 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 61: Frontiers of Electronic Structure Theory: Organics and Materials (jointly with O, HL)
TT 61.2: Vortrag
Mittwoch, 18. März 2015, 11:00–11:15, MA 004
Role of atomic multiplets in intermediate valence SmB6 and PuB6 systems — •Alexander B. Shick1, Alexander I. Lichtenstein2, and Mikhail I. Katsnelson3 — 1Institute of Physics, Academy of Sciences of the Czech Republic, Prague, Czech Republic — 2Institute of Theoretical Physics, University of Hamburg, Hamburg, Germany — 3Radboud University Nijmegen, The Netherlands
The materials with strong electron correlations are important because of the fundamental properties, and the technological applications. Recently, SmB6 (as well as PuB6) was proposed as 3D topological insulator [1]. The electronic structure calculations are performed combining the LDA with an exact diagonalization of the Anderson impurity model [2] for [Sm,Pu]B6. For the Sm atom in SmB6, intermediate valence ground state (GS) is found with the f-shell occupation ⟨ n4f ⟩=5.6. The GS is a singlet, and the first excited triplet state ∼ 3 meV higher in the energy. The f-orbital density of states is in agreement with experimental PE spectra. SmB6 is a narrow band insulator already in LDA, with the direct band gap of ∼ 10 meV. The electron correlations increase the band gap which now becomes indirect. For the Pu atom in PuB6, we also find intermediate valence (⟨ n5f ⟩=5.5) singlet GS. The calculations illustrate that many-body effects are relevant to form the indirect band gap, and support the idea of "topological Kondo insulator" in SmB6. [1] M. Dzero et al., Phys. Rev. Lett. 104, 106408 (2010); [2] A. B. Shick et al., Phys. Rev. B 87, 020505(R) (2013).