Evidence for electronically-driven ferroelectricity in the family of strongly correlated dimerized BEDT-TTF molecular conductors

Abstract

By applying measurements of the dielectric constants and relative length changes to the dimerized molecular conductor $\kappa$-(BEDT-TTF)${}_2$Hg(SCN)${}_2$Cl, we provide evidence for order-disorder type electronic ferroelectricity which is driven by charge order within the (BEDT-TTF)${}_2$ dimers and stabilized by a coupling to the anions. According to our density functional theory calculations, this material is characterized by a moderate strength of dimerization. This system thus bridges the gap between strongly dimerized materials, often approximated as dimer-Mott systems at 1/2 filling, and non- or weakly dimerized systems at 1/4 filling exhibiting charge order. Our results indicate that intra-dimer charge degrees of freedom are of particular importance in correlated $\kappa$-(BEDT-TTF)${}_2$X salts and can create novel states, such as electronically-driven multiferroicity or charge-order-induced quasi-1D spin liquids.

arXiv comment6 pages, 4 figures + Supplementary Information (8 pages, 8 figures)

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Cited by in corpus (25)

• Molecular Quantum Materials: Electronic Phases and Charge Dynamics in Two-Dimensional Organic Solids
• Impurity Moments Conceal Low-Energy Relaxation of Quantum Spin Liquids
• Low-Temperature Dielectric Anomalies at the Mott Insulator-Metal Transition
• Melting of charge order in the low-temperature state of an electronic ferroelectric
• Interplay of dipoles and spins in $\kappa$-(BEDT-TTF)${}_{2}X$, where $X=$ Hg(SCN)${}_2$Cl, Hg(SCN)${}_2$Br, Cu[N(CN)${}_2$]Cl, Cu[N(CN)${}_2$]Br, and Ag${}_2$(CN)${}_3$
• Ingredients for Generalized Models of $\kappa$-Phase Organic Charge-Transfer Salts: A Review
• Charge disproportionation in the spin-liquid candidate $\kappa$-(ET)${}_2$Cu${}_2$(CN)${}_3$ at 6 K revealed by ${}^{63}$Cu NQR measurements
• Lattice dynamics coupled to charge and spin degrees of freedom in the molecular dimer-Mott insulator $\kappa$-(BEDT-TTF)${}_2$Cu[N(CN)${}_2$]Cl
• Ferromagnetism out of charge fluctuation of strongly correlated electrons in $\kappa$-(BEDT-TTF)${}_2$Hg(SCN)${}_2$Br
• Spin Vortex Crystal Order in Organic Triangular Lattice Compound
• Anomalously field-susceptible spin soft-matter emerging in an electric-dipole liquid candidate
• First-principles study of the charge ordered phase in $\kappa$-D${}_3$(Cat-EDT-TTF/ST)${}_2$: Stability of $\pi$-electron deuterium coupled ordering in hydrogen-bonded molecular conductors
• Charge and spin interplay in a molecular-dimer-based organic Mott insulator
• Relaxation dynamics in the one-dimensional organic charge-transfer salt δ-(EDT-TTF-CONMe${}_2$)${}_2$Br
• Raman signatures of the strong intra- and inter-molecular charge oscillations in bis(ethylenedithio)-tetrathiafulvalene (BEDT-TTF) \k{appa}-phase salts
• Intriguing relaxor ferroelectricity in a polar CT crystal at the neutral-ionic interface
• Evidence for distortion-induced local electric polarization in $\alpha$-RuCl${}_3$
• Ultrafast modulation of covalency in GeTe driven by a ferroelectric soft mode
• Combined experimental and theoretical studies on glasslike transitions in the frustrated molecular conductors $\theta$-(BEDT-TTF)${}_{2}M{M}^{\prime }$(SCN)${}_4$
• Electronic correlations and spin frustration in the molecular conductors $\kappa$-(BEDT-TTF)${}_2$X probed by magnetic quantum oscillations
• Electronic properties of the dimerized organic conductor $\kappa$-(BETS)${}_2$Mn[N(CN)${}_2$]${}_3$
• Absence of superconductivity in the Hubbard dimer model for kappa-(BEDT-TTF)_2X
• ${}^{13}$C NMR observation of a nonmagnetic charge-ordered state in the organic conductor $\kappa$-(ET)${}_2$Hg(SCN)${}_2$Cl
• Spin liquid and ferroelectricity close to a quantum critical point in PbCuTe${}_2$O${}_6$
• Tuning Charge Order in $\kappa$-(BEDT-TTF)${}_2$Hg(SCN)${}_2$X (X=Br, Cl) via Uniaxial Strain