Magnetic properties of superconducting salts, (DODHT)${_{2}}$X (X = AsF${_{6}}$, PF${_{6}}$ and BF${_{4}}$)

The magnetic properties of organic superconductors (DODHT)$_{2}$X [ (1,4-dioxane-2,3-diyldithio)dihydro- tetrathiafulvalene; X = AsF$_{6}$, PF$_{6}$ and BF$_{4}\cdot $H$_{2}$O] were investigated by ESR and magnetic susceptibility measurements. At ambient pressure, the salts exhibited semiconducting behavior with some anomalies. The ESR linewidth gradually decreased and showed an inflection at the temperature where resistive anomaly was observed. The temperature dependence of the spin susceptibility estimated from the ESR signal intensity showed a broad maximum at 150 – 200 K. The correspondence of the temperature dependence of the magnetic susceptibility obtained by SQUID measurements to the ESR results and suggests low dimensional antiferromagnetic (AF) ordering, which is expected when charge ordering occurrs in the semiconducting – insulating region. Key words. Organic superconductor – magnetic property - electron spin resonance – charge ordering