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Charge disproportionation and Hund's insulating behavior in a five-orbital Hubbard model applicable to d^4 perovskites

Maximilian E. Merkel1*, Claude Ederer1*

1 Materials Theory, ETH Zürich, 8093 Zürich, Switzerland

* Corresponding authors emails: maximilian.merkel@mat.ethz.ch, claude.ederer@mat.ethz.ch
DOI10.24435/materialscloud:3s-b5 [version v1]

Publication date: Oct 29, 2021

How to cite this record

Maximilian E. Merkel, Claude Ederer, Charge disproportionation and Hund's insulating behavior in a five-orbital Hubbard model applicable to d^4 perovskites, Materials Cloud Archive 2021.184 (2021), doi: 10.24435/materialscloud:3s-b5.

Description

We explore the transition to a charge-disproportionated insulating phase in a five-orbital cubic tight-binding model applicable to transition-metal perovskites with a formal d^4 occupation of the transition-metal cation, such as ferrates or manganites. We use dynamical mean-field theory to obtain the phase diagram as a function of the average local Coulomb repulsion U and the Hund's coupling J. The main structure of the phase diagram follows from the zero band-width (atomic) limit and represents the competition between high-spin and low-spin homogeneous and an inhomogeneous charge-disproportionated state. This results in two distinct insulating phases: the standard homogeneous Mott insulator and the inhomogeneous charge-disproportionated insulator, recently also termed Hund's insulator. We characterize the unconventional nature of this Hund's insulating state. Our results are consistent with previous studies of two- and three-orbital models applicable to isolated t2g and eg subshells, respectively, with the added complexity of the low-spin/high-spin transition. We also test the applicability of an effective two-orbital (eg-only) model with disordered S=3/2 t2g core spins. Our results show that the overall features of the phase diagram in the high-spin region are well described by this simplified two-orbital model but also that the spectral features exhibit pronounced differences compared to the full five-orbital description.

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File name Size Description
README.txt
MD5md5:e7b45b65406066d6ab4a144204c8f828
3.7 KiB Description of content of tight_binding.tar.gz and pythtb_to_Hk_file.py
tight_binding.tar.gz
MD5md5:eaed503a6cf92ca6343444193777b59d
179.2 MiB tar.gz archive with all data and scripts needed to generate TB models, run DMFT on them and post-process results
pythtb_to_Hk_file.py
MD5md5:de5a8c724450f6f9f8917c2df7b7393f
5.0 KiB Python script to generate the necessary files for the triqs H(k) converter from the pythTB model

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Files and data are licensed under the terms of the following license: Creative Commons Attribution 4.0 International.
Metadata, except for email addresses, are licensed under the Creative Commons Attribution Share-Alike 4.0 International license.

External references

Journal reference (Paper where the data and plots are discussed)
Preprint (Preprint to the paper where the data and plots are discussed)

Keywords

dynamical mean-field theory metal-insulator transition charge disproportionation MARVEL/DD5

Version history:

2021.184 (version v1) [This version] Oct 29, 2021 DOI10.24435/materialscloud:3s-b5