Identifying Atomic Reconstruction at Complex Oxide Interfaces Using Quantitative STEM

Abstract

We present a novel electron microscopy characterization of atomic reconstruction at epitaxial complex oxide interfaces. One of the most important aspects of oxide heterostructures is the discontinuity in polarity at the interface, which can lead to many exciting new properties that cannot be observed in bulk materials, such as metal-insulator transitions and superconductivity (e.g. [1]). The conflict of polarity may also result in atomic and electronic reconstructions at the interface, which may directly affect the transport properties of the interface. However, identifying the exact atomic reconstruction at the interface is a challenging task because the reconstruction is usually confined to an interfacial region thinner than 1 unit cell. Cross-sectional TEM or STEM images can reveal some information about the interfacial reconstruction, but it is difficult to obtain the reconstruction pattern along the depth direction (parallel to the beam) from the projected image. Therefore the identification of interfacial reconstruction requires a technique that can acquire atomic scale 3-dimensional (3D) information.