Ferromagnetism and Colossal Magnetoresistance from the Coexistence of Comparable Charge and Spin Density Orders

摘要

We report a complete multicomponent mean-field-theory for the coexistence andcompetition of charge ordering (CO), antiferromagnetic (AFM) and ferromagnetic(FM) spin ordering in the presence of a uniform magnetic field. Doping the AFMor CO state always generates a ferromagnetic component. Itinerant FM, AFM andCO, necessarily coexist and compete in a particle-hole asymmetric system.Melting of large AFM-CO orders by small magnetic fields and the relatedphenomenon of Colossal Magnetoresistance (CMR) may arise whenever the CO andAFM order parameters have similar magnitude and momentum structure. Hole dopingfavors FM metallic states and CMR while electron doping favors AFM-CO states inagreement with the phase diagram of perovskite manganites.