Ferromagnetism of manganese compounds

It is shown on the basis of the notion of a strong electron-electron interaction in the unit cell that a ferromagnetic instability is possible in a system with hops between manganese cations and oxygen anions. The phase diagram for the existence of ferromagnetic ordering as a function of the degrees of underfilling n _p and n _t of the 2p ⁶ shell of oxygen and the 3t _g ⁶ shell of manganese, respectively, is constructed. Pis’ma Zh. éksp. Teor. Fiz. 66, No. 4, 254–259 (25 August 1997)