Relaxation dynamics in the one-dimensional organic charge-transfer salt δ-(EDT-TTF-CONMe2)2Br

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TitreRelaxation dynamics in the one-dimensional organic charge-transfer salt δ-(EDT-TTF-CONMe2)2Br
Type de publicationArticle de revue
AuteurFischer, JKH , Lunkenheimer, P. , Leva, C. , Winter, S. M , Lang, M. , Mézière, Cécile , Batail, Patrick , Loidl, A. , Manna, R. S
2, 4
EditeurAmerican Physical Society
TypeArticle scientifique dans une revue à comité de lecture
Date29 Juin 2018
Titre de la revuePhysical Review B
Mots-clésCharge order, charge transfer insulators, dielectric properties, dielectric spectroscopy, glass transition, thermal expansion, thermal techniques
Résumé en anglais

A detailed investigation of the charge-ordered charge-transfer salt δ−(EDT−TTF−CONMe2)2Br by thermal-expansion measurements and dielectric spectroscopy reveals three dynamic processes of relaxational character. The slowest one exhibits the characteristics of glassy freezing and is ascribed to the conformational dynamics of terminal ethylene groups of the organic molecules. Such a process was previously found for related charge-transfer salts where, however, the anions form polymerlike chains, in contrast to the spherical anions of the present material. Dielectric spectroscopy reveals two additional relaxational processes. The characteristics of the faster one are consistent with excitations of a one-dimensional Wigner lattice as recently observed in this material by infrared spectroscopy, which are also accompanied by conformational changes of the molecules. However, at low temperature the ethylene-group relaxation exhibits the cooperativity-induced dramatic slowing down that is typical for glassy freezing, while the defect-related Wigner-lattice excitation follows thermally activated behavior as expected for single-dipole relaxations.

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Titre abrégéPhys. Rev. B