Racah Materials: Role of Atomic Multiplets and Intermediate Valence in f -Electron Systems
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Racah Materials: Role of Atomic Multiplets and Intermediate Valence in f-Electron Systems A. I. Lichtenstein, J. Kolorenc, A. B. Shick and M. I. Katsnelson MRS Advances / FirstView Article / July 2016, pp 1 - 8 DOI: 10.1557/adv.2016.358, Published online: 16 May 2016
Link to this article: http://journals.cambridge.org/abstract_S2059852116003583 How to cite this article: A. I. Lichtenstein, J. Kolorenc, A. B. Shick and M. I. Katsnelson Racah Materials: Role of Atomic Multiplets and Intermediate Valence in f-Electron Systems. MRS Advances, Available on CJO 2016 doi:10.1557/adv.2016.358 Request Permissions : Click here
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MRS Advances © 2016 Materials Research Society DOI: 10.1557/adv.2016.358
Racah Materials: Role of Atomic Multiplets and Intermediate Valence in f-Electron Systems A. I. Lichtenstein1, J. Kolorenc2, A. B. Shick2, and M. I. Katsnelson3 1
University of Hamburg, Jungiusstrasse 9, 20355 Hamburg, Germany Institute of Physics, Czech Academy of Sciences, Slovance 2, 18221 Prague, Czech Republic 3 Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands 2
ABSTRACT The electronic structure of PuB6, an actinide analog of SmB6 , was investigated making use of a combination of the density functional theory (DFT), and the exact diagonalization (ED) of an effective discrete Anderson impurity model. Intermediate valence ground state with the f-shell occupation n4f =5.5 for the Pu atom in PuB6 is calculated. The 5f-shell magnetic moment is completely compensated by the moment carried by the electrons in the conduction band. Already in DFT, PuB6 is an insulator with a small amount of holes near the X-point, and the indirect band gap of ≈60 meV. This band gap becomes direct in DFT+ED calculations supporting the idea of "topological Kondo insulator" in PuB6. Connection between the electronic structure of PuB6 and -Pu is established. We propose that these materials belong to a new class of intermediate valence “Racah” materials with the multi-orbital "Kondo-like" singlet ground-state. INTRODUCTION Theoretical modeling of the electronic, structural, and magnetic character of actinide materials and their 5f-manifold states is very difficult. The standard electronic structure tools of solid state physics based on the density functional theory (DFT) cannot be taken as a reliable vehicle to explain the electronic, structural and magnetic properties of actinides and their compounds. The unique physical properties of actinides originate of their position at the localization-delocalization threshold, and require new many-body tools and concepts provided by the dynamical mean-field theory (DMFT) which is illustrated in Fig. 1. It is commonly accepted that 5f-electrons in light actinides form rather broad conduction bands whereas for the heavy actinides the 5f-states are atomic-like. Johan
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