Charge/orbital ordering structure in ordered perovskite SM1/2Ba1/2MnO3

In an A-site ordered perovskite marganite Sm1/2Ba1/2MnO3, a new charge/orbital ordering pattern was found at room temperature. Electron diffraction studies revealed a series of superlattice reflections with modulation vectors at q(2) = (1/2, 1/2, 1/2) as well as at q(1) = (1/4, 1/4, 0) in the tetragonal setting (a(p) x a(p) x 2a(p), a(p) being the cubic perovskite lattice parameter). Together with the results of the resonant X-ray scattering and the charge-transport and magnetization measurements, a new model for the three-dimensional charge/orbital ordering in the ordered perovskite is proposed.