FERROMAGNETIC DOMAIN STUDIES IN HIGHLY PERFECT METAL PLATELETS AND WHISKERS.
Final rept., 1 Dec 65-30 Nov 66,
GENERAL ELECTRIC CO SCHENECTADY N Y RESEARCH AND DEVELOPMENT CENTER
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Nearly perfect thin single-crystal platelets and submicron whiskers of nickel and nickel alloy were used to study nearly ideal ferromagnetic domain and domain wall structures and behavior. Applying fields to classically simple domain patterns leads to new observations of surface pinning and to the formation of several new types of double walls. One type is composed of 180 degree walls of mixed Neel-Bloch structure. Domain observations at the edges and corners of Ni-Co and Ni-Fe platelets with weak negative anisotropy revealed a new tulip pattern that makes clear the process of formation of edge echelons and corner chevrons. Precise determinations of saturation fields at platelet corners and ends were made by examining the resulting domain pattern at low field. Nucleation at the corners and edges of previously saturated thin platelets is observable in low positive and negative fields. Further platelet observations included a field induced stripe pattern in Ni-Co platelets with positive anisotropy, domain walls formed by magnetostrictive anisotropy, and details of spin directions in 180 degree domain walls with various sequences of Bloch walls, Neel walls, and Bloch lines. Individual single-domain nickel whiskers as thin as 600 A have been optically observed, handled, and tested in ferromagnetic nucleation studies. Author
- Electricity and Magnetism