Involvement of structural dynamics in charge-glass formation in strongly frustrated molecular metals

Tatjana Thomas, Yohei Saito, Yassine Agarmani, Tim Thyzel, Martin Lonsky, Kenichiro Hashimoto, Takahiko Sasaki, Michael Lang, Jens Müller

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


We present a combined study of thermal expansion and resistance fluctuation spectroscopy measurements exploring the static and dynamic aspects of the charge-glass formation in the quasi-two-dimensional organic conductors θ-(BEDT-TTF)2MM′(SCN)4 with M = Cs and M′ = Co,Zn. In these materials, the emergence of a novel charge-glass state so far has been interpreted in purely electronic terms by considering the strong frustration of the Coulomb interactions on a triangular lattice. Contrary to this view, we provide comprehensive evidence for the involvement of a structural glasslike transition at Tg∼90-100K. This glassy transition can be assigned to the freezing of structural conformations of the ethylene endgroups in the donor molecule with an activation energy of Ea≈0.32eV, and the concomitant slowing down of the charge-carrier dynamics is well described by a model of nonexponential kinetics. These findings disclose an important aspect of the phase diagram and calls for revisiting the present views of the glassy dynamics in the whole family of θ-(BEDT-TTF)2MM′(SCN)4. Our results suggest that the entanglement of slow structural and charge-cluster dynamics due to the intimate coupling of lattice and electronic degrees of freedom determine the charge-glass formation under geometric frustration.

Original languageEnglish
Article numberL041114
JournalPhysical Review B
Issue number4
Publication statusPublished - 2022 Jan 15

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics


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