Study of Strongly Correlated Electronic System of Low-Dimension in Organic Conductors

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The purpose of the present study is to clarify effects of the Coulomb correlation among electrons to properties of low-dimensional electronic system in organic conductors.In (BEDT-TTF)_2KHg(SCN)_4 and its family we found a geometrical effect of the two-dimensional Fermi surface to the magnetoresistance. We found also an antiferromagnetic-like state presumably due to instability of another Fermi surface of one-dimension. The anitiferromagnetic state was found to be present at low temperatures below 8 K, under weak magnetic fields below 23 T, and at low pressures below 5 Kbar.In TMTSF salts another geometrical effect to the magneto-resistance was found. In addition we presented answers to questions about puzzling properties of the field-induced spin density waves. The high-field limiting state was found to have the quantum number of zero.In DCNQI salts the reentrance transition was investigated in detail. Electronic properties of this class of materials were found to be understood in terms of the Peierls transition in the pi band of DCNQI molecular stacks and the Mott transition in the d band due to copper ions.In conclusion one can say that all factors of low-dimensionality, the electron correlation, the electron-phonon interaction, and weak three-dimensionality play essential roles in electronic properties of these materials.