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

• Main Authors: Dolbin, A.V., Khlistuck, M.V., Eselson, V.B., Gavrilko, V.G., Vinnikov, N.A., Basnukaeva, R.M., Konstantinov, V.A., Nakazawa, Y.
• Format: Article
• Language: English
• Published: Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України 2017
• Series: Физика низких температур
• Subjects: Низкоразмерные и неупорядоченные системы
• Online Access: http://dspace.nbuv.gov.ua/handle/123456789/175357

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.