| Research Abstract |
The purpose of this project is to develop the molecular design for the organic superconductor with two-dimensional electronic structure and for the control of the dimensionality of the electronic structure. Our strategy is to form a flat molecular surface in the direction parallel to the molecular plane. On the basis of this idea, we have studied several organic donors, BEDT-TSeF (BETS), BMDT-TTF, ETIT, DMET-TSeF, TMET-STF and so on. Among them, BETS, BMDT-TTF, and ETIT provided a lot of tow-dimensional metals stable down to 4.2 K, which have confirmed the applicability of our molecular design. The isostructural salts (TMET-STF)_2X (X=ClO_4, BF_4) have a novel crystal structure, which consists of two types of donor columns ; the one is one-dimensional and the other is two-dimensional. Cation radical salts (DMET-TSeF)_2X have quasi one-dimensional electronic structure. The salts with X=AuI_2 and I_3, were found to be ambient pressure superconductors. In the case of X=AuI_2, AuBr_2, and AuC1_2, the field induced spin density wave (FISDW) states were observed. These are the first FISDW states in organic systems other than the TMTSF family.
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