Theoretical investigation on the magnetic interaction of the tetrathiafulvalene-nitronyl nitroxide stacking model: possibility of organic magnetic metals and magnetic superconductors

The possibility of realizing ferromagnetic conducting crystals was investig ated theoretically. Detailed theoretical calculations were carried out for tetrathiafulvalene-nitronyl nitroxide (TTF-NN) and one- and two-hole doped states of its dimer. The result indicated that the sign of effective exchan ge interactions between TTF-NN is largely dependent on the stacking modes a nd hole doping stales. Well-controlled slacking and hole doping modes of sp in-polarized TTF-NN molecule led to positive effective exchange integrals ( J(ab)), indicating its possibility as an organic ferromagnetic metal. Thus, charge-transfer (CT) complexes with radical groups will exhibit a ferromag netic interaction and electronic conductivity may be expected along the don or column, if appropriate columnar stacking and partially hole-doped state were realized. Implications of the calculated results are discussed ill rel ation to the field-induced superconductivity in the field-effect-transistor (FET) and spin FET configurations. (C) 2001 Elsevier Science Ltd. All righ ts reserved.