Improvements in Domain Study with the Conventional Bitter Method by Digital Image Processing System

Abstract

The paper presents improvements in magnetic domain investigation with the conventional Bitter colloid method achieved thanks to the application of a digital image processing (DIP) system. The system capabilities are demonstrated referring to selected examples of the magnetic structure in a thin nickel–iron film, sintered Nd–Fe–B permanent magnets, a ferrimagnetic garnet plate, and bulk cobalt monocrystals. With the aid of our DIP system, high quality domain images, which were not possible before, could be obtained and analyzed in more detail. As a consequence, the previously reported problems related to the study of the domain configuration in soft magnetic materials and at the basal surface of bulk cobalt monocrystals by the conventional Bitter pattern technique were overcome and improvements over earlier results were made.

Study of thermally evaporated thin permalloy films by the Fresnel mode of TEM and AFM

“…It offers high spatial resolution and high sensitivity to small variations in the magnetization, and consequently compares favorably with Bitter pattern technique [22,23]. Thanks to the mentioned features of TEM, the magnetization distribution and the character of domain walls present in the investigated films could be precisely determined.…”

Study of the Magnetic Microstructure of Thin Cobalt Films by Bitter Pattern Method and Lorentz Microscopy

“…1b. The latter image was obtained after applying digital procedures for contrast and sharpness enhancement [3] to the original image from Fig. 1a.…”

“…The DIP system used and its capabilities are described in detail in Ref. [3]. The magnetic microstructure of the films 40 nm thick was also observed in a transmission electron microscope (TEM) using the Fresnel mode.…”

Studies of the domain structure of anisotropic sintered SmCo5 permanent magnets

“…Detailed descriptions of the digital systems used and demonstrations of their capabilities are presented in Refs. [23,24]. As a consequence, high-quality domain images could be obtained and analyzed not only qualitatively but also quantitatively.…”

“…This is understandable, however, because in the case of the former surface the stray magnetic fields are much weaker (they are produced by domain walls, and additionally also by existing misaligned grains and surface defects) than those associated with the latter surface (they are mainly produced by domains). To obtain considerably better quality images of the magnetic microstructure on the surface parallel to the alignment axis, the original images were subjected to digital procedures for contrast and sharpness improvement (the latter procedure known as unsharp masking [24]). Fig.…”