Magnetic properties of the doped manganites: A meanfield

The main features of the experimental observations of Urushibara et al. on the magnetic properties of La Sr MnO are fitted to a mean-field model. Using the ideas of Zener and of Goodenough, the observed shift in the Neel temperature, the transition from antiferromagnetism to ferromagnetism and the parabolic variation in Curie temperature with Sr fraction are seen to be compatible with semicovalent exchange interactions through hybridized O 2p orbitals together with a double-exchange-like ferromagnetic interaction through holes introduced by the substitution of divalent for trivalent cations.