2. Domain Observation Techniques (106 pages)

2.1 Introduction

Domain observation techniques are classified according to the field they are sensitive to:

  • magnetic induction B,
  • magnetic polarization J, or
  • magnetic stray field H

generated by the poles of the magnetization pattern

2.2 Bitter Patterns

Fig. 2.6c,d:   The heads of the "tadpole" pattern on slightly misoriented (110) silicon-iron sheets (c) are due to some subsurface accumulation of magnetic "charge" which does not show up in surface methods like the magneto-optical Kerr effect (d)

2.3 Magneto-Optical Methods

Fig. 2.18   Depending on the plane of incidence in a Kerr microscope either the domain pattern (b) or the substructure of the domain walls (a) can be made visible on a (100)-oriented SiFe crystal

2.4 Transmission Electron Microscopy (TEM)

Fig. 2.30    The Differential Phase Contrast method of transmission electron microscopy offers quantitative information at high resolution. The pictures show the horizontal (a) and the vertical (b) magnetization components of a closed-flux domain pattern in a thin-film Permalloy element (Courtesy J.N. Chapman)

2.5 Electron Reflection and Scattering Methods

Fig. 2.38c   Two components of the surface magnetization on an iron whisker, made visible with Electron Polarization Analysis. Very high resolution and quantitative information about the magnetization at the very surface of a sample can be achieved with this method (Courtesy J. Unguris)

2.6 Mechanical Microscanning Techniques

Fig. 2.43d,e   Magnetic force microscopy on the basal plane of a cobalt crystal. Image processing can reveal "susceptibility contrast" (d) and "charge contrast" (e), two imaging modes which are unavailable with other techniques. (d) and (e) are the sum and the difference of images taken with opposite polarity of the tip magnetization, respectively

2.7 X-ray, Neutron and Other Methods

Fig. 2.48b    X-ray topography displays 90° domain walls and dislocations in a silicon iron sheet at the same time (Courtesy J. Miltat)

2.8 Integral Methods Supporting Domain Analysis


Fig. 2.55d    The average legth of a ferromagnetic crystal (L3) can be a measure of the volume fraction of transversely magnetized domains (v3)

2.9 Comparison of Domain Observation Methods


Fig. 2.56c   One of several criteria used in the comparison of domain observation techniques. SEM = Scanning (reflection) electron microscopy, TEM = transmission electron microscopy, MFM = magnetic force microscopy

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Prof. Dr. Rudolf Schäfer

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Email: r.schaefer@ifw-dresden.de