High resolution structural and compositional mapping of the SrTiO$_{3}$/LaFeO$_{3}$ interface using chromatic aberration corrected energy filtered imaging

Interfaces between insulating polar perovskites have demonstrated a wealth of electronic and magnetic properties. Understanding and predicting the properties of a specific interface requires atomic level knowledge of interface structure and chemistry. Electron microscopy is capable of this task, and has been frequently applied to oxide interfaces using a combination of high-angle angular dark field scanning transmission electron microscopy (HAADF-STEM) and electron energy-loss spectroscopy (EELS). Energy-filtered TEM (EFTEM) captures a full image for a given energy losses, allowing a larger field of view than typical for STEM-EELS in far less time. However, EFTEM has not, to date, demonstrated the spatial resolution of STEM-EELS due to the limits set by chromatic aberration C$_{c}$. This study of LaFeO$_{3}$/SrTiO$_{3}$ demonstrates that C$_{c}$ correction enhances the resolution of EFTEM for elemental mapping, allowing a unit cell-by-unit cell analysis of the concentration gradients across the SrTiO$_{3}$/LaFeO$_{3}$ interface. The charge distribution at the interface will be discussed.