Electron channeling contrast imaging of anti-phase boundaries in coherently strained La_(0.7)Sr_(0.3)MnO_3 thin films on (110)-oriented SrTiO_3

摘要

Electron channeling contrast imaging (ECCI) was used to characterize coherently strained La_(0.7)Sr_(0.3)MnO_3 (LSM) films grown on (110)_(cubic)-SrTiO_3 (STO) and (100)_(orthorhombic-NdGaO_3 (NGO). We focus on the characterization of a relatively low density (1-3 μm/μm~2) of meandering loops (MLs) found in the LSM film on STO and absent in the film on NGO. The MLs exhibit a uniform contrast variation from the background and a strong contrast dependence on the diffraction vector g. The MLs are quantitatively consistent with LSM anti-phase boundaries (APBs) having a displacement vector R=1/2[001]_(LSM). These APBs are consistent with a "double positioning" degeneracy of tilted octahedra along [001]_(LSM) on untilted octahedra along [001]_(STO). The results highlight the non-destructive capacity of ECCI to characterize extended defects in oxide films.