Time-resolved Measurements Using Spin-polarized Pulsed Electron Beam in Transmission Electron Microscopy

Abstract

Time-resolved measurements in transmission electron microscopy (TEM) offer the possibility of revealing ultrafast phenomenon with nanometer spatial resolution, allowing the analysis of nonuniform materials, functional materials, and advanced nano-devices. A high-quality pulsed electron beam, with high brightness, narrow energy width, and high spin-polarization, was realized by installing a semiconductor-type photocathode having a negative electron affinity surface to an electron gun in the TEM system.

We conducted time-resolved measurements of electron energy-loss spectrum with picosecond pulsed electron beam in the TEM, and elucidated electron-phonon and phonon-phonon relaxation processes in photo-excited gold nanoparticles. Furthermore, the intensity interference of charged fermions was realized by temporally modulated spin-polarized electrons. The coherent spin-polarized electron beam facilitates the extraction of intrinsic quantum interference. These application results pave the way for a new analytical method for the ultrafast dynamics of electrons and lattices in materials, in addition to quantum measurements in electron microscopes.