Domain-structure relaxation in the tetragonal-to-orthorhombic phase transition of the layered perovskite Sr1.8La0.2Mn1-yFeyO4

An in situ observation of the tetragonal-to-orthorhombic phase transition in Fe-substituted Sr1.8La0.2MnO4 by transmission electron microscopy revealed that the domain structure changes, as a relaxation phenomenon, took place during the aging for the formation of the orbital ordered state. At each aging temperature, the final banded domain structure could be produced from any starting state. The characteristic features of the domain-structure relaxation found in this study are also discussed in terms of a coupling between the local Jahn-Teller and long-range dilational distortions.