抄録
Crystal grains and domain patterns of Ni–Fe alloy films which were condensed on cleaved surfaces of heated NaCl in a vacuum of 5×10−5 torr were studied by transmission electron microscopy and electron diffraction. Magnetic anisotropy was also measured by a torque magnetometer for thin films. The substrate temperature was varied between room temperature and 600°C. The films obtained range from polycrystal to nearly perfect single crystals. The degree of perfection of the crystal is classified into several types. The magnetic domain patterns and crystal anisotropies of the films depend on the composition and also on the degree of perfection of the films. Polycrystalline films are, in general, found to consist of domains of irregular shapes with curved walls and ripple structure within the domains. In good epitaxial films, however, the domains have a regular cross-hatched shape and when the films are magnetized parallel to one of the crystal anisotropy axes, the films are composed of linear domain walls almost without any ripple. Ni films, which have a large magnetostriction are apt to be influenced by internal and external stresses, which affect the domain pattern and the torque curve. Even for good epitaxial Ni films the stress induced anisotropy is often superior to the crystal anisotropy.
The measured values of crystal anisotropy constant K1 of good epitaxially grown films of Ni–Fe alloys agree with those of the bulk materials, but, in pure Ni and pure Fe films, they are 1.5–2 times as large as the bulk values.
