ORIGIN OF THE RESISTIVITY ANOMALIES OF (EDT-TTF)[M(DMIT)(2)] (M=NI, PD)

alpha-(EDT-TTF)[Ni(dmit)(2)] comprises crossing columns of EDT-TTF and Ni(dmit)(2) and exhibits unique metallic behaviour with a characteristic resistivity peak at around 14 K. The possibility of the development of the superstructure was examined down to 9 K by using a low-temperature imaging plate X-ray system, but no extra X-ray reflections could be found below 14 K. The 14 K anomaly is, therefore, thought not to originate from charge density wave (CDW) instability New phases of gamma-(EDT-TTF)[Pd(dmit)(2)] and gamma-(EDT-TTF)[Ni(dmit)(2)] were found. gamma-(EDT-TTF)[Pd(dmit)(2)] has parallel columns of EDT-TTF and Pd(dmit)(2) and shows a resistivity anomaly around 80 K. Below 80 K, X-ray satellite reflections indicating CDW formation were observed. gamma-(EDT-TTF)[Ni(dmit)(2)] undergoes a metal-insulator transition at around 100 K.