Effect of anisotropic strain on the charge ordering behavior in Bi 0.4 Ca 0.6 MnO 3 films

Anisotropic strain has a significant influence on the charge ordering (CO) behavior in Bi 0.4 Ca 0.6 MnO 3 (BCMO) films on (110) SrTiO 3 substrates. Effect of film thickness on the CO behavior in BCMO films was investigated at 103K 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.