Features of Highly Correlated Electronic States in the Simple Perovskite Manganite Sr1−xSmxMnO3 with 0.15 ≤ x ≤ 0.50

The C- and A-type antiferromagnetic orderings have been reported in the highly correlated electronic manganite Sr1−xSmxMnO3 (SSMO) with the simple perovskite structure in the composition range of 0.34 ≤ x ≤ 0.46. Because these antiferromagnetic orderings should be coupled to orbital orderings, the crystallographic features of SSMO samples prepared with 0.15 ≤ x ≤ 0.50 have been investigated, mainly by X-ray powder diffraction and transmission electron microscopy, to understand the detailed features of the corresponding orbital-ordered states. It was found that around 100 K, for instance, the C-type orbital-ordered (COO) state was observed for 0.15 ≤ x ≤ 0.42, the orbital-modulated (OM) state for 0.44 ≤ x < 0.50, and the coexistence state of both ferromagnetic Pnma (I) and paramagnetic Pnma (II) regions for x = 0.50, where the OM state was characterized by a transverse lattice modulation with an incommensurate periodicity. Neither the A-type orbital-ordered state nor the CE-type state involving both orbita...