The determination of transition noise by Lorentz electron microscopy

The transition noise in a highly oriented magnetic film medium is analyzed with reference to the development of quantitative techniques to relate micromagnetic domain images obtained by Lorentz electron microscopy to the measured noise and signal for the medium. In general, the agreement between electronically derived and image-derived noise is excellent. It is demonstrated that micromagnetic imaging and analysis for this type of recording medium is sufficiently quantitative to justify using Lorentz micrographs to explore the origin and nature of transition noise. The proper interpretation of spectral analyses of finite field-of-view images is also clarified, i.e. it is shown that for noise analysis, only the minima of the spectra potentially contain valid noise information. The lobes contain mostly (scattered) signal information