Low Temperature Physics: 42, 788 (2016); https://doi.org/10.1063/1.4962750
Fizika Nizkikh Temperatur: Volume 42, Number 9 (September 2016), p. 1007-1012    ( to contents , go back )

Peculiarities of thermal expansion of quasi-two-dimensional organic conductor κ-(BEDT–TTF)2Cu[N(CN)2]Cl

A.V. Dolbin1, M.V. Khlistuck1, V.B. Eselson1, V.G. Gavrilko1, N.A. Vinnikov1, R.M. Basnukaeva1, V.V. Danchuk1, V.A.Konstantinov1, and Y. Nakazawa2

1B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine 47 Pr. Nauky, Kharkiv 61103, Ukraine
E-mail: dolbin@ilt.kharkov.ua

2Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan

Received April 14, 2016

Abstract

Linear coefficient of thermal expansion α(Т) of single crystal (BEDT–TTF)2Cu[N(CN)2]C1 was studied along the crystal layers using the method of precise capacitive dilatometry in the temperature range 2–285 K. It is positive in this direction over the entire temperature range. Anomalies of thermal expansion were observed at 29–30 K and 74–80 K. The anomaly near 30 K is, apparently, due to the transition between the paramagnetic phase and the antiferromagnetic insulator state. Peak of α(Т) at 78 K corresponds to a phase transition related to orientational disordering of ethylene groups in dimers of BEDT–TTF. A broad maximum of α(Т) in the temperature range 40–70 K, is apparently explained by fluctuations of charge within the dimers, and by spin fluctuations, which first increase with increasing temperature, and then decrease in process of thermal disordering of dimers.

PACS: 65.40.De Thermal expansion; thermomechanical effects;
PACS: 63.22. Np Layered systems.

Key words: organic molecular conductors, (BEDT–TTF)2Cu[N(CN)2]C1, thermal expansion.

Published online: July 25, 2016

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