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arXiv · 2503.11547

Tuning Charge Order in $\kappa$-(BEDT-TTF)$_2$Hg(SCN)$_2$X (X=Br, Cl) via Uniaxial Strain

Jesse Liebman·Svetlana Torunova·John A. Schlueter·Elena Zhilyaeva·Natalia Drichko
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Abstract

In condensed matter physics, experimental control over material properties reflects a deep understanding of the underlying physics. In recent years, meaningful progress has been made towards a description of the physics of correlated electron systems, but examples of control of these systems remain rare. In this work, we confirm a phase diagram theoretically proposed for organic Mott insulators. We use $\kappa$-(BEDT-TTF)$_2$Hg(SCN)$_2$X (X=Br,Cl) (BEDT-TTF = bis(ethylenedithio)tetrathiafuvalene) materials as experimental realization of the proposed model and demonstrate the ability to tune them both ways across a phase border between a Mott insulator with a uniformly distributed charge and a charge ordered state through the application of uniaxial strain. We induce charge order at 33 K in the quantum dipole liquid material $\kappa$-(BEDT-TTF)$_2$Hg(SCN)$_2$Br through the application of tensile strain of 0.4% along the c-axis. We suppress charge order down to 10 K in $\kappa$-(BEDT-TTF)$_2$Hg(SCN)$_2$Cl by applying a tensile strain of 1.6% along the b-axis. We use Raman scattering spectroscopy to probe the charge state through analysis of charge sensitive molecular vibrations and a low frequency mode of collective dipole fluctuations close to the phase border.

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Jesse Liebman, Svetlana Torunova, John A. Schlueter, Elena Zhilyaeva, Natalia Drichko. 2025-03-14. Tuning Charge Order in $\kappa$-(BEDT-TTF)$_2$Hg(SCN)$_2$X (X=Br, Cl) via Uniaxial Strain. https://doi.org/10.1103/qzr7-dd5f

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