Noritaka Miyamoto

Element-Specific Magnetic Domain Imaging of (Nd, Dy)-Fe-B Sintered Magnets Using Scanning Transmission X-Ray Microscopy

We demonstrate an element-specific observation of magnetic domains in thermally demagnetized Nd-Fe-B and (Nd, Dy)-Fe-B sintered magnets using scanning transmission X-ray microscopy (STXM). Clear chemical and magnetic contrast images with the 30-nm spatial resolution were taken by STXM. Both maze-like magnetic domains and stripe magnetic domains with their widths of 200-300 nm are observed in both Nd-Fe-B and (Nd, Dy)-Fe-B sintered magnets. In both sintered magnets, multidomain structures are mostly formed within each grain-that is, magnetic domains are likely to be terminated at the grain boundaries. Stripe domains are originated from the grains with the (001)-axis misoriented to the sample normal. From the comparison between chemical and magnetic images, it is found that no clear magnetic domain is observed in Nd-rich phase at grain boundary triple points. Furthermore, it is also found that the interface between Nd2Fe14B phase and Nd-rich phase is chemically abrupt. Similar magnetic domain patterns are observed in Nd-Fe-B and (Nd, Dy)-Fe-B sintered magnets.

Visualization of magnetic dipolar interaction based on scanning transmission X-ray microscopy

Using scanning transmission X-ray microscopy (STXM), in this report we visualized the magnetic dipolar interactions in nanocrystalline Nd-Fe-B magnets and imaged their magnetization distributions at various applied fields. We calculated the magnetic dipolar interaction by analyzing the interaction between the magnetization at each point and those at the other points on the STXM image.