Professor Judy J. Cha
Phase transformations of nanoscale systems using in situ TEM
Many nanoscale systems rely on phase transformations for switching their functionalities in response to stimuli. Thus, investigation of such phase transformations and subsequent correlation to changes in materials properties are critical. Here, we use in situ transmission electron microscopy (TEM) as a tool to study directly how phase transformations occur, deviate, and be controlled at the nanoscale under either thermal or electrical stimuli.
I will discuss two phase transformation examples: IBM’s confined phase change memory (PCM) devices with a metal surfactant layer, which showed a record endurance of 2x1012 programming cycles and metallic glass nanostructures that are used to test the limits of classical nucleation theories at the nanoscale. In both cases, atomic scale in situ TEM investigations reveal detailed and unexpected phenomena, which can guide us to build better models and theories. If time allows, I will briefly cover superconducting behaviors of topological superconductor nanowires (indium-doped tin telluride nanowires) and the importance of sample quality in dictating exotic quantum phases.