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

Abstract

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.

arXiv comment5+4 pages, 4 figures

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Cited by in corpus (41)

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• Switching between Mott-Hubbard and Hund physics in moiré quantum simulators
• Accuracy of ghost-rotationally-invariant slave-boson theory for multiorbital Hubbard models and realistic materials
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• Correlation strength, orbital-selective incoherence, and local moments formation in the magnetic MAX-phase Mn${}_2$GaC
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• Multiple insulating phases due to the interplay of strong correlations and lattice geometry in a single-orbital Hubbard model
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• A unified phase diagram of F-doped LaFeAsO by means of NMR and NQR parameters
• Rashba-metal to Mott-insulator transition
• Persistent half-metallic ferromagnetism in a (111)-oriented manganite superlattice
• Competing Correlated Insulators in multi-orbital systems coupled to phonons
• Calculation of screened Coulomb interaction parameters for the charge-disproportionated insulator CaFeO${}_3$
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• Real-Space Switching of Local Moments Driven by Quantum Geometry in Correlated Graphene Heterostructures
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• Long-term memory magnetic correlations in the Hubbard model: A dynamical mean-field theory analysis
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• Many-body electronic structure, self-doped double-exchange, and Hund metallicity in 1T-CrTe2 bulk and monolayer