Физика Низких Температур: Том 43, Выпуск 12 (Декабрь 2017), c. 1740-1744    ( к оглавлению , назад )

Thermal expansion of organic superconductor κ-(D4-BEDT-TTF)2Cu{N(CN)2}Br. Isotopic effect

A.V. Dolbin, M.V. Khlistuck, V.B. Eselson, V.G. Gavrilko, N.A. Vinnikov, R.M. Basnukaeva, and V.A. Konstantinov

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

Y. Nakazawa

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

Received June 23, 2017

Аннотация

Linear thermal expansion coefficient (LTEC) of single crystal κ-(D4-BEDT-TTF)2Cu[N(CN)2]Br was studied across the crystal layers in the temperature range 2–290 K using the method of precise capacitive dilatometry. Below Tc = 11.6 K the LTEC of the sample had a small negative value, which is apparently due to the transition from the paramagnetic metal in the superconducting state. There was a bend of temperature dependence of the LTEC, which shows broad peak around 40 K and can be attributed to the elastic lattice anomaly around the end-point of Mott boundary. A sharp jump in the LTEC values and hysteresis was observed in the area of Tg ~ 75–77 K, what is likely explained by the transition in a glass-like state. The isotope effect in the thermal expansion is discusses, which manifested itself in a shift of the phase transitions in comparison with fully deuterated BEDT-TTF sample.

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

Ключевые слова: organic molecular conductors, κ-(D4-BEDT-TTF)2Cu[N(CN)2]Br, thermal expansion, isotopic effect.

Published online: October 25, 2017