Cryogenic Atomic Resolution and 4D STEM Imaging for Energy and Quantum Materials

Abstract

Four-dimensional STEM (4D-STEM) has been attracting significant attention in recent years in the electron microscopy community. In this method, nearly all electrons are collected after they interact with specimen. A ‘complete’ set of information about the specimen is encoded in 4D-STEM datasets and can be reconstructed via applying various phase retrieval methods or virtual detectors. In particular, information such as highresolution charge density mapping, local potential distributions and chemical bonding, which were challenging to obtain before, have recently been demonstrated [1-6]. These new capabilities are critical to the research of quantum and energy materials, where local charge and potential define the function of materials and devices. However, many of the materials in these two categories require the characterization to be performed at a low temperature. For example, exotic states in quantum materials usually only occur at a low temperature (T); and lithium metal and solid electrolyte interphase layers in battery materials are extremely sensitive to electron irradiation induced heating. The largest challenge in in situ cryo-STEM for materials science currently is the limited stage and temperature stability, making imaging at atomic resolution or at intermediate temperatures difficult [7]. Achieving a sufficient stability is even more challenging for Cryo-4D-STEM, where a longer acquisition is usually needed than for STEM imaging using a conventional detector.