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

Abstract

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 were realized. Implications of the calculated results are discussed in relation to the field-induced superconductivity in the field-effect-transistor (FET) and spin FET configurations.