A method is presented here for observing micromagnetic structures in ferromagnetic specimens. Experimental apparatuses for forming electron holograms and for reconstructing optical images are described. Special attention is paid to factors limiting measurement precision. The technique is applied to thin ferromagnetic films, for the purpose of observing fine details of magnetization distribution in a contour map of the electron phase.

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Electron holography was employed for experiments involving a high-density magnetic recording, in which it was possible to directly observe streams of magnetic flux. The magnetic flux distribution in recorded films, and the maximum packing density in high-coercivity evaporated cobalt film were investigated. With magnetic longitudinal recording the resultant highest density was 170 000 bits per inch. This experiment has proven that electron holography is useful for the study of magnetic recording.

Magnetic characteristics have been investigated for a magnetoresistive thin-film sensor biased using a permanent magnet thin film. Here, Co-Pt thin film is applied to the device as a bias film. Such microlithographed Co-Pt thin films show the same magnetic properties as as-sputtered films. Biasing strength depends on the permanent magnet film thickness, its composition or magnetic properties, and the biasing angle. The output of the sensor is very high.

The [111] oriented Pt/Fe multilayered films were fabricated by electron beam evaporation in an ultra-high vacuum of 10-8 Pa. Keeping the thickness of Fe at 0.2 nm corresponding to one atomic monolayer (ML), several samples with the different Pt layer thickness (np 1) from I to 8 ML were deposited on the Si-wafer covered with 20 nm thick Au(lll) buffer layer. XRD patterns of the samples with np 1 ::: 2 showed well-resolved superlattice peaks. Superlattie periods from XRD and atomic compositions evaluated by RBS spectra almost agree with the designed ones. All the films are ferromagnetic even at room temperature. The magnetization decreases with the increase of np 1 at 300 K, suggesting the two dimensional effect for high np 1 • For the sample with np 1 =8, the perpendicular magnetic anisotropy was observed at 5 K. Details of the XRD intensity analysis indicate the alloy layer formation.