Ferromagnetic Domains in Single-Crystal Permalloy Platelets

Thin single-crystal Permalloy platelets with up to 30% iron have been grown nonepitaxially by the reduction of mixed Ni-Fe halides. Those with weak negative magnetocrystalline anisotropy, 〈100〉 edges, and (100) surfaces display a “tulip” closure-domain pattern that reveals the mode of formation of the more complicated echelon and chevron patterns observed in pure nickel platelets. The tulip pattern may appear as a modified form of the Néel-strip closure structure that Bates and co-workers have studied extensively to obtain quantitative information concerning low-field domain processes. The platelets are thus useful for extending this work to smaller, thinner, and more nearly ideal specimens. Platelets in a region near 5000 Å thick and 5% iron have 〈100〉 domains and stripes even though K1<0.