Evidence for Electronically Driven Ferroelectricity in a Strongly Correlated Dimerized BEDT-TTF Molecular Conductor

Elena Gati, Jonas K.H. Fischer, Peter Lunkenheimer, David Zielke, Sebastian Köhler, Felizitas Kolb, Hans Albrecht Krug Von Nidda, Stephen M. Winter, Harald Schubert, John A. Schlueter, Harald Olaf Jeschke, Roser Valentí, Michael Lang

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Abstract

By applying measurements of the dielectric constants and relative length changes to the dimerized molecular conductor κ-(BEDT-TTF)2Hg(SCN)2Cl, we provide evidence for order-disorder type electronic ferroelectricity that is driven by the 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 nondimerized or weakly dimerized systems at 1/4 filling, exhibiting a charge order. Our results indicate that intradimer charge degrees of freedom are of particular importance in correlated κ-(BEDT-TTF)2X salts and can create novel states, such as electronically driven multiferroicity or charge-order-induced quasi-one-dimensional spin liquids.

Original languageEnglish
Article number247601
JournalPhysical Review Letters
Volume120
Issue number24
DOIs
Publication statusPublished - Jun 14 2018

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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    Gati, E., Fischer, J. K. H., Lunkenheimer, P., Zielke, D., Köhler, S., Kolb, F., Von Nidda, H. A. K., Winter, S. M., Schubert, H., Schlueter, J. A., Jeschke, H. O., Valentí, R., & Lang, M. (2018). Evidence for Electronically Driven Ferroelectricity in a Strongly Correlated Dimerized BEDT-TTF Molecular Conductor. Physical Review Letters, 120(24), [247601]. https://doi.org/10.1103/PhysRevLett.120.247601