Author/Authors :
Ito، نويسنده , , H. and Yokochi، نويسنده , , Y. and Tanaka، نويسنده , , H. and Kuroda، نويسنده , , S. and Kanehama، نويسنده , , R. and Umemiya، نويسنده , , M. and Miyasaka، نويسنده , , H. and Sugiura، نويسنده , , K. -i. and Yamashita، نويسنده , , M.، نويسنده ,
Abstract :
Transport and ESR measurements have been performed on organic semiconductors synthesized by the diffusion method. For (BEDT-TTF)Cu2Br4, a pressure of 1 GPa raises the conductivity by up to one order of magnitude, but does not alter the semiconducting nature. By the ESR measurements, we find no Cu2+ signals, indicating that the BEDT-TTF molecules are divalent. The Hall carrier concentration increases exponentially with temperature, approaching the spin concentration evaluated by the low-temperature ESR from π-electrons. Thermopower measurements also support the contribution of the thermally activated electronic carriers. For (BEDTTTF)2Cu3Br7(H2O), the conductivity increases twice by applying a pressure of 0.8 GPa.
Keywords :
organic conductors , Hall effect , Thermopower , electron spin resonance , Conductivity
