Stability of electronic states in the layered perovskite Sr_2-xNd_xMnO₄

The electronic system in the layered perovskite Sr_2-xNd_xMnO₄ is characterized as a two-dimensional e_g-electron system. In order to understand the stability of electronic states in the Nd-content region of 0 ≤ x ≤ 0.50, the crystallographic features of this manganite have been investigated by transmission electron microscopy. The increase in the Nd-content led to the orbital ordered state in 0.10 ≤ x ≤ 0.25 and the charge and orbital ordered state in 0.25 ≤ x < 0.45. In particular, it was found that the orbital ordering accompanied the C-type antiferromagnetic ordering at lower temperatures, and that the transition to the charge and orbital ordered states was strongly suppressed in x > 0.35.