In situ Lorentz microscopy in an alternating magnetic field

An alternating magnetizing system has been developed for in situ Lorentz microscopy for soft magnetic materials in an alternating magnetic field. The electron trajectory in the system is discussed using a simulation based on a simple model. It is clarified that the frequency and amplitude of the alternating magnetic field and the defocus of the objective mini lens can be selected as desired values. The system is successfully applied to the observation of domain wall motion in a soft magnetic material, Fe84.9Al5.5Si9.6 (wt%) (Sendust). The system is very promising for investigating interactions between domain walls and lattice defects in various kinds of soft magnetic materials.