Low-temperature crystal and band electronic structures of metallic M(dmit)2(M=Ni, Pd) compound

The crystal structure of α-[(CH3)2(C2H5)2N][Ni(dmit)2]2(dmit=1,3-dithiol-2-thione-4,5-dithiolate) was determined at 11 K by use of newly developed X-ray system based on the imaging plate(IP) equipped with closed cycle He refrigerator. The space group of C2/c of the high-temperature phase changes to P21/c at low temperature. The extended Huckel tight-binding band calculation based on the 11K structure and the X-ray evidence showing the appearance of the twofold superlattice gave two-dimensional Fermi surfaces, which are consistent with those derived from the experiments on the magnetoresistance oscillation.