Magnetic Switching in Ni-Fe Single-Crystal Films

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Abstract
Quasistatic magnetic switching in Ni‐Fe single‐crystal films for different orientations of the reversal fields were studied both experimentally by Lorentz microscopy and theoretically. It was found that the switching processes can be explained quantitatively by a theory combining the Stoner‐Wohlfarth rotational switching curve and the theoretical wall motion switching curve derived in this paper from a simple model. Eight typical switching processes are illustrated by Lorentz micrographs with explanation for two types of films; one type has a higher ratio of coercive force to biaxial anisotropy field than the other. Both wall motion switching and rotational switching were observed. In some cases, the complete switch takes place in two separate consecutive stages, each stage corresponding to a different easy axis direction 90° apart, each stage being by a different switching mechanism. Cross‐tie walls were observed in single‐crystal films in the proper thickness range. Although the films studied had nearly zero magnetostriction and a good single‐crystal structure, all films exhibited magnetization ripple in the Lorentz micrographs.