• Letter

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, and Jens Müller
Phys. Rev. B 105, L041114 – Published 31 January 2022
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Abstract

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 Tg90100K. 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 Ea0.32eV, 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.

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  • Received 1 September 2021
  • Revised 3 December 2021
  • Accepted 20 January 2022

DOI:https://doi.org/10.1103/PhysRevB.105.L041114

©2022 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Tatjana Thomas1, Yohei Saito1, Yassine Agarmani1, Tim Thyzel1, Martin Lonsky1, Kenichiro Hashimoto2,3, Takahiko Sasaki3, Michael Lang1, and Jens Müller1,*

  • 1Institute of Physics, Goethe University Frankfurt, 60438 Frankfurt (M), Germany
  • 2Department of Advanced Materials Science, University of Tokyo, 277-8561 Chiba, Japan
  • 3Institute for Materials Research, Tohoku University, 980-8577 Sendai, Japan

  • *j.mueller@physik.uni-frankfurt.de

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Issue

Vol. 105, Iss. 4 — 15 January 2022

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