  A reversible structural transition of an epitaxial La2/3Sr1/3MnO3 film
deposited on the LaAlO3 substrate has been investigated by means of in situ
high-resolution transmission electron microscopy (HREM) and electron
diffraction, combined with image and diffraction calculations. We observe that
the crystallographic symmetry of the film can be lowered via electron beam
irradiation, leading to a rhombohedral-monoclinic transition. This transition
can be attributed to the cooperating effect of the mismatch stress and the
irradiation-induced thermal-stress.
