Microchip-calorimetry of organic charge transfer complex which shows superconductivity at low temperatures

We carried out thermodynamic measurements of organic charge transfer complex of κ-(BEDT-TTF)2Cu[N(CN)2]Br, where BEDT-TTF is bis(ethylenedithio)tetrathiafulvalene by TCG3880 chip device in order to examine capability of the chip calorimeter at low temperature region and under magnetic fields. TCG3880 chip is mounted on a 3He cryostat available in combination with a superconductive magnet up to 7 T. Thermal anomalies related to the glass-like freezing of ethylene groups of BEDT-TTF molecules and the superconductive transition were observed. A frequency dependence of the thermal anomaly of the glass formation and a magnetic fields dependence of the thermal anomaly of the superconductive transition are reported. The results presented in this work demonstrate that the TCG3880 is quite useful for thermodynamic investigations of the organic charge transfer complex with much reduced sample quantity as compared with those of relaxation and adiabatic calorimetry.

► Organic charge transfer salt of κ-(BEDT-TTF)2Cu[N(CN)2]Br shows superconductivity.
► We succeeded to detect thermal anomaly microchip device TCG3880.
► Development details of the calorimeter and the detection system is presented.
► The magnetic fields dependence shows typical character of layered superconductor.