Single-nanoparticle switching dynamics visualized by 4D electron microscopy

4D electron microscopy enables simultaneous real- and reciprocal-space imaging of nanostructured materials with unprecedented spatio-temporal resolns. Here we apply it to visualize the photoswitching dynamics of single spin-crossover nanocrystals. The nanoparticles are largely influenced by the frictional and thermal characteristics of the interface, which are unique on the level of a single nanoparticle, while averaged out in conventional studies on nanoparticles ensembles. Theor. modeling reveals the non-equil. thermoswitching pathways in the phase diagram of the spin transition