Imaging Heterogeneity in 2DMaterials with Photoemission Electron Microscopy
Two-dimensional (2D) materials have taken a central role in condensed matter research and next-generation device design due to their compact size, turnability, and novel electronic properties. Heterogeneity and anisotropy in these materials are particularly important as micro- and nano-scale interfaces host emergent phenomena and give rise to new functionalities. In this talk, I will present our work investigating these types of structures with photoemission electron microscopy(PEEM). I will first discuss our results mapping the antiferroelectric domain structure in β′-In2Se3. Although the antiferroelectric order means that this material contains net-zero spontaneous polarization, domains remain dichroic, enabling their imaging with optical probes. With polarization-dependentPEEM, we interrogate the domain structure with nano-scale precision, makequantitative domain orientation assignments, and connect the atomic distortionsto the optically addressable mesoscale structure. Avenues for modifying domain arrangements and generating multiphase heterostructures will also be explored. Finally, I will also discuss our recent investigations of coherent light-matter interactions with PEEM. MoOCl2 is a highly anisotropic 2D material that hosts in-plane hyperbolic plasmon polaritons in the visible range. Spatiotemporal analysis of these modes will be presented in which we visualize their real-time propagation and hyperbolic focusing.