Charge ordering in the perovskite manganites

Charge ordering is a phenomenon generally observed in mixed-valent transition metal oxides. The perovskite manganites are especially interesting because long-range ordering of the Mn3+ and Mn4+ ions in these materials is linked to antiferromagnetic spin ordering, the long-range ordering of the Mn3+ orbital and the associated lattice distortions. The early experiments and the progress of current state of charge ordering were overviewed in this article. The abnormal change of the resistivity, magnetization, lattice parameter and ultrasonic velocity and attenuation around the charge ordering transition with the effects of cation size, chemical substitution, pressure, and magnetic field on the charge ordering were also discussed.