RESUMO
A side-entry specimen holder capable of applying a 0.5-tesla in-plane magnetic-induction field for in-situ transmission electron microscopy was developed. Three miniaturized electromagnets with 300â¯×â¯300-µm pole area and 180-µm pole gap are stacked along the electron-beam path in the holder. The middle magnet is used for magnetizing the specimen, which is inserted into the pole gap by using a 40-µm-width cantilever for atomic-force microscopy. The upper and lower magnets are used to keep the electron beam parallel to the optical axis. Magnetic-field magnitude was determined on the basis of experimentally measured electron-deflection angles and induction-field profiles along the electron-beam path calculated by finite element electromagnetic simulation. Magnetization reversal in 300-nm-thick Nd-Fe-B magnets from the saturated state was in-situ observed by using the holder and a 1-MeV cold-field-emission transmission electron microscope. The observation revealed that domain-wall pinning occurred in different manners at the c-plane and non-c-plane grain boundaries. The holder was thereby shown to be useful for analysis of magnetization-reversal behaviors of hard magnetic materials.
RESUMO
Electron holographic vector field electron tomography visualized three-dimensional (3D) magnetic vortices in stacked ferromagnetic discs in a nanoscale pillar. A special holder with two sample rotation axes, both without missing wedges, was used to reduce artifacts in the reconstructed 3D magnetic vectors. A 1 MV holography electron microscope was used to precisely measure the magnetic phase shifts. Comparison of the observed 3D magnetic field vector distributions in the magnetic vortex cores with the results of micromagnetic simulations based on the Landau-Lifshitz-Gilbert equation showed that the proposed technique is well suited for direct 3D visualization of the spin configurations in magnetic materials and spintronics devices.