Development and applications of ultrafast transmission electron microscopy

We present a review on the development and applications of ultrafast transmission electron microscopy (UTEM) at Institute of Physical and Chemical Research (RIKEN). We introduce the UTEM system for the pump-probe transmission electron microscopy (TEM) observation in a wide temporal range. By combining the UTEM and pixelated detector, we further develop five-dimensional scanning TEM (5D STEM), which provides the ultrafast nanoscale movie of physical quantities in nanomaterials, such as crystal lattice information and electromagnetic field, by convergent-beam electron diffraction (CBED) and differential phase contrast imaging technique. We show our recent results on the nanosecond-to-microsecond magnetic skyrmion dynamics observed by Lorentz TEM (LTEM) and photoinduced acoustic wave generation in the picosecond regime by bright-field TEM and electron diffraction measurements by UTEM. We also show the demonstration of the 5D STEM on the quantitative time (t)-dependent strain mapping by CBED with an accuracy of 4 ps and 8 nm and the ultrafast demagnetization under a zero magnetic field observed by differential phase contrast with 10 ns and 400 nm resolution.