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Information Center for Mathematical Science

세미나

Information Center for Mathematical Science

세미나

2018 KAIST Physics Seminar
Title Molecular Mott state in the deficient spinel GaV4S8
Date 2019-01-09
Speaker Heung-Sik Kim(Rutgers University)
Sponsors 2019-01-09
Host KAIST
Place E6-2, 2nd Fl. #2501
Abstract In this work, we investigated theoretically the Mott-insulating phase of a deficient spinel chalcogenide GaV4S8, which is known to form a tetrahedral V_4 S_4 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 intra-cluster 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.