Effect of External Pressure on the Metal–Insulator Transition of the Organic Quasi-Two-Dimensional Metal κ-(BEDT-TTF)<sub>2</sub>Hg(SCN)<sub>2</sub>Br

The metal–insulator transition in the organic quasi-two-dimensional metal κ-(BEDT-TTF)<sub>2</sub>Hg(SCN)<sub>2</sub>Br at <i>T</i><sub>MI</sub> ≈ 90 K has been investigated. The crystal structure changes during this transition from monoclinic above &l...

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Bibliographic Details
Main Authors: Sergei I. Pesotskii, Rustem B. Lyubovskii, Gennady V. Shilov, Vladimir N. Zverev, Svetlana A. Torunova, Elena I. Zhilyaeva, Enric Canadell
Format: Article
Language:English
Published: MDPI AG 2022-11-01
Series:Magnetochemistry
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Online Access:https://www.mdpi.com/2312-7481/8/11/152
Description
Summary:The metal–insulator transition in the organic quasi-two-dimensional metal κ-(BEDT-TTF)<sub>2</sub>Hg(SCN)<sub>2</sub>Br at <i>T</i><sub>MI</sub> ≈ 90 K has been investigated. The crystal structure changes during this transition from monoclinic above <i>T</i><sub>MI</sub> to triclinic below <i>T</i><sub>MI</sub>. A theoretical study suggested that this phase transition should be of the metal-to-metal type and brings about a substantial change of the Fermi surface. Apparently, the electronic system in the triclinic phase is unstable toward a Mott insulating state, leading to the growth of the resistance when the temperature drops below <i>T</i><sub>MI</sub> ≈ 90 K. The application of external pressure suppresses the Mott transition and restores the metallic electronic structure of the triclinic phase. The observed quantum oscillations of the magnetoresistance are in good agreement with the calculated Fermi surface for the triclinic phase, providing a plausible explanation for the puzzling behavior of κ-(BEDT-TTF)<sub>2</sub>Hg(SCN)<sub>2</sub>Br as a function of temperature and pressure around 100 K. The present study points out interesting differences in the structural and physical behaviors of the two room temperature isostructural salts of κ-(BEDT-TTF)<sub>2</sub>Hg(SCN)<sub>2</sub>X with X = Br, Cl.
ISSN:2312-7481