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Molecular Mott state in the deficient spinel GaV4S8

Heung-Sik Kim, Kristjan Haule, and David Vanderbilt
Phys. Rev. B 102, 081105(R) – Published 6 August 2020
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Abstract

In this study, we investigated theoretically the Mott-insulating phase of a deficient spinel chalcogenide GaV4S8, which is known to form a tetrahedral V4S4 cluster unit that results in molecular orbitals (MOs) with a narrow bandwidth in the noninteracting limit. We used a cluster extension of charge self-consistent embedded dynamical mean-field theory to study the impact of strong intracluster correlations on the spectral properties as well as the structural degrees of freedom of the system. We found that the strong tetrahedral clustering renders the atomic Mott picture ineffective, and that the resulting MO picture is essential to describe the Mott phase. It was also found that, while the spectral properties can be qualitatively described by the truncation of the Hilbert space down to the lowest-energy MO, a proper description of the structural degrees of freedom requires the inclusion of multi-MO correlations that span a larger energy window. Specifically, we found that the lowest-energy MO description overemphasizes the clustering tendency, while the inclusion of the Hund's coupling between the lower- and higher-energy MOs corrects this tendency, bringing the theoretically predicted crystal structure into good agreement with the experiment.

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  • Received 22 October 2018
  • Revised 24 February 2020
  • Accepted 24 July 2020

DOI:https://doi.org/10.1103/PhysRevB.102.081105

©2020 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Heung-Sik Kim1,2, Kristjan Haule1, and David Vanderbilt1

  • 1Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854-8019, USA
  • 2Department of Physics, Kangwon National University, Chuncheon 24341, Korea

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Issue

Vol. 102, Iss. 8 — 15 August 2020

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