EFFECTS OF ELECTRON-ELECTRON INTERACTIONS ON THE FERROMAGNETIC STATE IN AN ORGANIC POLARONIC FERROMAGNET

A Peierls-extended Hubbard model is used to study the effects of elect ron-electron interactions on the possible ferromagnetic ground state i n the polaronic ferromagnet. Considering the strong electron-phonon co upling and allowing for full lattice relaxation, the system is optimiz ed by a set of self consistent iterative equations. The formation ener gies of polarons with different spin arrangements are calculated. The results of calculation indicate that the possible ferromagnetic ground state of the system will be affected dramatically by the onsite and i ntersite e-e interactions. However, for appropriate electron-electron interactions the ferromagnetic state can become a stable ground state.