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

摘要

The possibility of realizing ferromagnetic conducting crystals was investigated 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 exchange interactions between TTF-NN is largely dependent on the stacking modes and hole doping states. Well-controlled stacking and hole doping modes of spin-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 ferromagnetic interaction and electronic conductivity may be expected along the donor column, if appropriate columnar stacking and partially hole-doped state was realized. Implications of the calculated results are discussed in relation to the field-induced superconductivity in the field-effect-transistor (FET) and spin FET configuration.