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arXiv · 1703.01894

The metal-insulator transition in the organic conductor $\beta^{\prime\prime}$-(BEDT-TTF)$_{2}$Hg(SCN)$_{2}$Cl

Weiwu Li·Eva Rose·Minh Vu·Ralph Hüber·Andrzej Łapiński·Roman Świetlik·Svetlana A. Torunova·Elena I. Zhilyaeva·Rimma N. Lyubovskaya·Martin Dressel
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Abstract

We explore the nature of the metal-insulator transition in $\beta^{\prime\prime}$-(BEDT-TTF)$_{2}$Hg(SCN)$_{2}$Cl by x-ray, electrical transport, ESR, Raman and infrared investigations. Magnetic and vibrational spectroscopy concurrently reveal a gradual dimerization along the stacking direction $a$, setting in already at the crossover temperature of 150K from the metallic to the insulating state. A spin gap $\Delta_\sigma = 47$meV is extracted. From the activated resistivity behavior below 55K a charge gap $\Delta_\rho=60$meV is derived. At $T_{\rm CO} = 72$K the C=C vibrational modes reveal the development of a charge-ordered state with a charge disproportionation of $2\delta_{\rho}=0.34e$

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Weiwu Li, Eva Rose, Minh Vu, Ralph Hüber, Andrzej Łapiński, Roman Świetlik, Svetlana A. Torunova, Elena I. Zhilyaeva, Rimma N. Lyubovskaya, Martin Dressel. 2017-03-06. The metal-insulator transition in the organic conductor $\beta^{\prime\prime}$-(BEDT-TTF)$_{2}$Hg(SCN)$_{2}$Cl. https://doi.org/10.1063/1.4997198

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