Domain Observation Techniques

Abstract

In this chapter methods to observe the magnetic microstructure are critically examined. For each method the principle, the basic experimental procedure, an outline of the theory, special techniques, and the potential are reviewed, followed by a discussion of merits and shortcomings of the method. A final section is devoted to a comparison of the various techniques in tabular form.Sketch 2.3.

Characterization Methods along the Process Chain of Electrical Steel Sheet—From Best Practices to Advanced Characterization

“…Grey methods are very elaborate and are mainly meant to address fundamental research questions. Right now, the domain structure is mostly considered in academia (Bitter imaging [ 64 ], neutron grating interferometry [ 66 ]), however, if reference Bitter imaging patterns of specific characteristics, such as high residual stresses, unfavourable orientations or grain boundaries, can be identified, it could become a great tool to quickly access qualitative data about the final magnetic properties based on the microstructure and texture. The domain structure could potentially link the microstructure and texture to the magnetic properties.…”

“…The basic principle is based on the accumulation of Fe 3 O 4 particles along horizontal surface stray fields, which result from the domain structure underneath the surface. In this context, it must be considered that the free surface alters the domain structure and therefore bulk information can only be extracted indirectly [ 64 ]. Here, colloidal Fe 3 O 4 nanoparticles are used, a so-called ferrofluid.…”

“…While magnetic force microscopy is limited to small scales, Kerr and Bitter imaging both reveal domain structures at the microscale. However, Hubert et al found that some domain structures can only be visualised by Bitter imaging, while others may only be visualised by Kerr microscopy [ 64 ].…”

High Throughput Biological Analysis Using Multi-bit Magnetic Digital Planar Tags

“…Arrays of micron-sized magnetic elements of 20 µm height with different aspect ratios (aspect ratio = height / width) and shapes were fabricated and studied to optimize the magnetic properties of digital planar tags. For the remote sensing method, we utilized a full-field magneto-optical Kerr microscope to observe the magnetic domain configuration [13,14], due to its high sensitivity to surface magnetization direction. The width of the measured elements were 1 µm, 2 µm, 3 µm, 4 µm, 6 µm and 8 µm, respectively, which gave a wide range of aspect ration between 1:20 to 1:2.5.…”