Superconducting properties of organic composites: blends of βco-(ET)2I3 with paraffin and polycarbonate

The superconducting properties of mixtures of microcrystalline powder of β CO -(ET) 2 I 3 (ET = bis(ethylenedithio)-tetrathiafulvalene) and paraffin or polycarbonate in different mass ratios were studied. Temperature-dependent DC-magnetisation measurements were performed by use of a SQUID magnetometer. The superconducting volume fraction and the onset temperature of the composites depends on the concentration and on the polymer matrix. This is attributed to the pressure exerted on β CO -(ET) 2 I 3 by the contraction of the polymer matrix.