Lorentz microscopy study on magnetization reversal process in single-domain state in perovskite-type manganite

The phenomenon of ferromagnetic domain switching, which occurred in a colossal magnetoresistive manganite La_0:25Pr_0:375Ca _0:375MnO₃, was studied by sophisticated transmission electron microscopy techniques. Lorentz microscopy observations revealed the size dependence of the magnetization reversal behaviors. A small single-domain (70 nm) exhibited a direct switching process to another single-domain form, while a large single domain (150 nm) showed a multiple-domain configuration before the transformation to another single-domain state. We also demonstrated significant magnetic interaction in an assembly of single domains; i.e., neighboring single domains underwent magnetization reversal simultaneously. The results provide useful information for a deeper understanding of the switching process in a single-domain state, which can be observed in many advanced materials related to magnetic data storage media.