Development of precession Lorentz transmission electron microscopy

Abstract

Lorentz transmission electron microscopy (LTEM) is a powerful tool for high-resolution imaging of magnetic textures, including their dynamics under external stimuli and ultrafast nonequilibrium conditions. However, magnetic imaging is often hindered by non-magnetic diffraction contrast arising from inhomogeneous sample deformation or a non-parallel electron beam. In this study, we develop a precession LTEM system that can suppress diffraction contrast by changing the incident angle of the electron beam relative to the sample in a precessional manner. By comparing LTEM images acquired at different precession angles ($θ$), we show that diffraction contrast is significantly reduced with increasing $θ$. However, large $θ$ values lead to an undesired broadening of the magnetic contrast, highlighting the importance of optimizing $θ$. Furthermore, defocus-dependent measurements reveal that magnetic contrast is particularly improved at small defocus values, suggesting that precession LTEM can achieve higher spatial resolution. These findings demonstrate the potential of precession LTEM as a powerful technique for studying magnetic dynamics.