Charge disproportionation, mixed valence, and Janus effect in multiorbital systems: A tale of two insulators

Multiorbital Hubbard models host strongly correlated 'Hund's metals' even for interactions much stronger than the bandwidth. We characterize this interaction-resilient metal as a mixed-valence state. In particular it can be pictured as a bridge between two strongly correlated insulato...

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Bibliographic Details
Published in:arXiv.org 2019-05
Main Authors: Isidori, Aldo, Berovic, Maja, Fanfarillo, Laura, Luca de' Medici, Fabrizio, Michele, Capone, Massimo
Format: Article
Language:English
Subjects:
Chromates
Coupling
Disproportionation
Insulators
Online Access:Get full text
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Summary:Multiorbital Hubbard models host strongly correlated 'Hund's metals' even for interactions much stronger than the bandwidth. We characterize this interaction-resilient metal as a mixed-valence state. In particular it can be pictured as a bridge between two strongly correlated insulators: a high-spin Mott insulator and a charge-disproportionated insulator which is stabilized by a very large Hund's coupling. This picture is confirmed comparing models with negative and positive Hund's coupling for different fillings. Our results provide a characterization of the Hund's metal state and connect its presence with charge disproportionation, which has indeed been observed in chromates and proposed to play a role in iron-based superconductors.
ISSN:2331-8422
DOI:10.48550/arxiv.1810.01899