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Structural dynamics in the organic conductor $κ − {(BETS)}_{2} Mn {[N {(CN)}_{2}]}_{3}$

Owen Ganter ^1,*, Tatjana Henrichs ^2,*, Yassine Agarmani ², Steffi Hartmann ², Mark Kartsovnik³, Stephen Winter ¹, Michael Lang ², and Jens Müller ²

¹Department of Physics and Center for Functional Materials, Wake Forest University, Winston-Salem, North Carolina 27109, USA
²Institute of Physics, Goethe-University Frankfurt, 60438 Frankfurt (M), Germany
³Dresden High Magnetic Field Laboratory (HLD-EMFL), Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany

^*These authors contributed equally to this work.

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Phys. Rev. Materials 10, 104416 – Published 20 October, 2026

DOI: https://doi.org/10.1103/tkl7-ynwy

Abstract

The layered organic conductor $κ − {(BETS)}_{2} Mn {[N {(CN)}_{2}]}_{3}$ is a strongly correlated electron system exhibiting a metal-insulator transition at $T_{MI} \approx 25 K$ and unusual equilibrium and nonequilibrium dynamics above and below $T_{MI}$ , respectively, caused by electronic ferroelectricity. However, at higher temperatures ( $T^{*} = 102 K$ ), another transition, associated with the formation of an incommensurate superstructure, has been reported, but its origin has not been clarified. By using resistance noise spectroscopy to investigate the low-frequency charge carrier dynamics as well as thermal expansion measurements, we find strong indications for a structural order-disorder transition of the BETS molecules' terminal ethylene groups, which manifests itself in a pronounced maximum in the noise magnitude around $T^{*} \approx 100 K$ . Performing computational studies of the energy landscapes of the BETS cations and the Mn[N(CN) $_{2}]_{3}$ polymeric anion, we find evidence suggesting that the observed structural transition is due to a possibly glassy freezing of the dicyanamide ligands in the anion layer.

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Structural dynamics in the organic conductor $κ − {(BETS)}_{2} Mn {[N {(CN)}_{2}]}_{3}$

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Structural dynamics in the organic conductor κ−(BETS)2Mn[N(CN)2]3

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Physics Subject Headings (PhySH)

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References (44)

Structural dynamics in the organic conductor $κ − {(BETS)}_{2} Mn {[N {(CN)}_{2}]}_{3}$