Rolf Erni, Trond Henninen, Feng Wang, Marta Bon, Debora Keller, Nabeel Ahmad, Marta D. Rossell, Marco Campanini

Electron Microscopy Center, Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland

Different approaches of using STEM to study the evolution and physical properties of nanomaterials are presented. When exploring the dynamics and stability of tiniest clusters of Pt atoms at elevated temperatures, we benefit from the high spatial resolution of aberration-corrected STEM and overcome the limited temporal resolution by applying an unusual fast scanning mode. This results in large sets of noisy data that require advanced data processing including machine learning and molecular dynamics simulations. In contrast, it is the limited depth of field of an aberration-corrected STEM probe which improves the resolution in liquid cell STEM while controlling nucleation and growth mode of metallic nanoparticles by the electron beam. Using differential phase contrast STEM, electrostatic fields, poten-tials and charges of individual atoms can be mapped. This is applied to study the periodic modulation of the ferroelectric polarization of a doped multiferroic material at atomic resolution.