Effect of anisotropic strain on the charge ordering behavior in Bi0.4Ca0.6MnO3 films

Anisotropic strain has a significant influence on the charge ordering (CO) behavior in Bi0.4Ca0.6MnO3 (BCMO) films on (110) SrTiO3 substrates. Effect of film thickness on the CO behavior in BCMO films was investigated at 103 K using transmission electron microscopy. It was found that the film has undergone a structural transformation with the increase of film thickness, i.e., from no modulation to a localized incommensurate modulation and further to a commensurate modulation. The distinctive thickness-dependent CO transition has a close relationship with the anisotropic strain relaxation process. Structural models are proposed to explain the modulated structures in the films.