Novel orbital ordering induced by anisotropic stress in a manganite thin film.
A novel structure of orbital ordering is found in a Nd0.5Sr0.5MnO3 thin film, which exhibits a clear first-order transition, by synchrotron x-ray diffraction measurements. Lattice parameters vary drastically at the metal-insulator transition at 170 K (= T(MI)), and superlattice reflections appear below 140 K (= T(CO)). The electronic structure between T(MI) and T(CO) is identified as A-type antiferromagnetic with a d(x2-y2) ferro-orbital ordering. The new type of antiferro-orbital ordering characterized by the wave vector (1/4 1/4 1/2) in cubic notation emerges below T(CO). The accommodation of the large lattice distortion at the first-order phase transition and the appearance of the novel orbital ordering are brought about by the anisotropy in the substrate, a new parameter for the phase control.
Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba 305-0801, Japan.
Y
Y
Wakabayashi
D
D
Bizen
H
H
Nakao
Y
Y
Murakami
M
M
Nakamura
Y
Y
Ogimoto
K
K
Miyano
H
H
Sawa