Magnetic properties of C-60-TDAE and TTFxC60Bry

The magnetic properties of C-60-TDAE and TTFxC60Bry may be described by the multi-band extended Hubbard model and the local configuration interaction method comparing the energy of the spin singlet and the spin triplet of a two-electron problem, Both the exchange and on site repulsion interactions play important roles in magnetism, For the half-filled single band system for most of the realistic lattice distances only antiferromagnetic long range order is allowed. For the C-60-TDAE and TTFxC60Bry systems, a multi-band description is more suitable. The condition of ferromngnetic long range order in a two-band system is given, Ferromagnetism can occur in C-60-TDAE and TTFxC60Bry.