Change in charge and orbital alignment upon antiferromagnetic transition in the A-site-ordered perovskite manganese oxide RBaMn2O6 (R=Tb and Sm) -: art. no. 140408

A neutron-diffraction study on an A-site-ordered perovskite manganite RBaMn2O6 (R=Tb) has revealed that the magnetic structure is characterized by two modulation vectors, (1/2 0 1/4) and (1/4 1/4 1/4), in the primitive cubic setting. The appearance of the magnetic order is accompanied by change in stacking of charge-ordered/orbital-ordered MnO2 sheets along the c axis, which has also been confirmed by electron-diffraction and x-ray-diffraction studies on the R=Tb and Sm compounds. The charge ordering in the antiferromagnetic phase is an unprecedented one, i.e., NaCl type, which is stabilized by the ordering of R and Ba in the A site.