Influence of crystalline structures on the domain configurations in controlled mesoscopic ferromagnetic wire junctions

A role of crystalline structures on domain wall formation is investigated by magnetic force microscopy (MFM) using mesoscopic wire junctions of both epitaxial bcc Fe and polycrystalline permalloy. Three sets of structures were fabricated with ferromagnetic wires (30 nm thick, $\text{0.2⩽w⩽50\hspace{0.17em}μ}\mathrm{m}$ wide and 200 μm long); straight wires, two wires connected at the ends (L shapes), and crosses. Fe samples show complicated domain configurations due to magnetocrystalline anisotropy, while permalloy samples show simple domain with shape anisotropy. These results show that spin configurations at the junction can be precisely tuned by varying not only the shape and the size but also the crystalline structures of the sample.