Advanced Cryogenic Electron Microscopy for Quantum Materials

In this presentation, I will provide an overview of our recent advancements in cryogenic microscopy characterization of quantum materials. I will highlight the interplay of electron, spin, and lattice degrees of freedom, and reveal the significant roles of heterogeneity and disorder at cryogenic temperatures when materials are subjected to external electric, magnetic, and photonic excitations. Specifically, I will present our low-temperature diffuse scattering analysis, which maps the photoinduced dynamics of charge density waves and the associated population evolution of various phonon branches. Additionally, I will discuss the use of cryogenic Lorentz phase microscopy to investigate the transformations among topological chiral spin states, including skyrmions, under applied electric and magnetic fields. Our development of a liquid-helium-free cryogenic sample holder capable of maintaining temperatures below 6K with long holding times and millikelvin temperature stability and control for autonomous electron microscopy will also be discussed.<br/><br/>I would like to acknowledge the electron microscopy group at CMPMS, BNL, for their assistance. This work was supported by the US DOE/BES-MSED under Contract DE-SC0012704.