Micro/magnetic structural development in Co-Ni-Cr and Co-Ni-Cr/Cr films for longitudinal recording media

Abstract

A series of Co-Ni-Cr and Co-Ni-Cr/Cr films have been examined using transmission electron microscopy in conventional bright/dark-field imaging, selected-area diffraction, convergent beam electron diffraction, as well as in Lorentz electron microscopy imaging mode. The crystallographic orientation and magnetic domain structure have been characterized as a function of film thickness. The results indicate that amorphous Co-Ni-Cr films form prior to the formation of small randomly oriented equiaxed grains during deposition on amorphous substrates. As the film thickness increases, some of the small grains grow preferentially with their c axis parallel to film plane, but others with their c axis at an angle of 62° from the film plane. Longitudinal domain structures of the films were found to consist of Néel walls associated with cross-tie walls and Bloch lines. Each domain contains a large amount of the magnetic ripple-type structure.