Atomic resolution STEM-EELS studies of defects and local structural distortions in oxide interfaces

Abstract

Doped complex oxides show a wide range of interesting properties due to a strong interplay andcompetition between lattice, spin, and charge degrees of freedom. In these systems, subtle changes inlocal structure or chemistry may result in colossal responses in macroscopic physical behavior. In thistalk we will apply atomic resolution aberration corrected scanning transmission electron microscopy(STEM) and electron energy-loss spectroscopy (EELS) to the study of the chemistry and local structurearound defects, near complex oxide interfaces, and grain boundaries. Thanks to spherical aberrationcorrection, both spatial resolution and sensitivity limits attainable in the STEM have improved down tothe single-atom level, resulting in unprecedented contrast and signal-to-noise ratio improvements in both imaging and EELS. We will discuss a few examples where atomic resolution compositional mapping constitutes a key task to understand the system physical properties, highlighting the importance of considering artifacts during quantification.