Thermodynamic Measurements
of Organic Conductors
by Schick-Type Micro-Chip Devices

We have applied the commercially available thermodynamic chip device (TCG-3880) supplied by Xensor Co. Ltd. for low temperature thermodynamic investigation of organic superconductor κ-(BEDT-TTF)2Cu[N(CN)2]Br, when BEDT-TTF is an abbreviation of bis(ethylenedithio)tetrathiafuluvalene. The temperature dependence of ac temperature modulation signals were measured with varying frequencies. The thermal anomaly related to the glass freezing of the ethylene group of BEDT-TTF molecules was observed. In the low temperatures region, the superconductive peak and its magnetic fields dependence were detected using a 3He apparatus. The chip calorimeter is available even in the low temperature region, if we can amplify the signal effectively.

(by Y. Muraoka and Y. Nakazawa)

	Fig.1 Block diagram of the detection system of the present calorimeter.
	Fig.2 Temperature dependence of the heat capacity of κ–(BEDT–TTF)2Cu[N(CN)2]Br obtained under 0.5 Hz, 1 Hz, and 13 Hz. A glass transition temperature increased with an increase of the excitation frequencies.
	Fig.3 Temperature dependence of the heat capacity around the superconductive temperature of κ–(BEDT–TTF)2Cu[N(CN)2]Br obtained under 0 T, 1 T, 4 T, and 7 T. The thermal anomaly under zero field is suppressed with the increase of magnetic field.