Ferromagnetic Domain Studies in Highly Perfect Metal Platelets

摘要

Ferromagnetic domain and domain-wall structures and behavior, as observed in nearly perfect single-crystal platelets of nickel and nickel alloy, are the subject of the report. Results of primary interest are: (1) the formation of ferromagnetic domain structures in platelets is shown to be a micromagnetic process involving nucleation of Bloch lines, gradual variations in the directions of magnetization, magnetostatic interactions between domain walls, and topological constraints. (2) The structures of four kinds of stripe patterns have been determined. All involve magnetic moment rotations parallel to (110) planes, either through 109 degrees (for Stripe 1, which has pseudopositive anisotropy) or through 71 degrees. Stripe 4 achieves appreciable internal flux closure by forming a helical structure. (3) Data of domain wall type vs platelet thickness and composition have been plotted to show the regions of existence for Neel, crosstie, Bloch, and intermediate (metastable bright) walls, and for the four types of stripe structures. (Author)