Nucleation of Ferromagnetic Domains in Iron Whiskers

Abstract

Nucleation fields up to 483 oe have been experimentally observed for the reversal of magnetization in regions of nearly perfect iron whiskers about 5 μ thick. This is near the theoretical limit ${\text{2K}}_1{\mathrm{/M}}_s\text{\hspace{0.17em}(\hspace{0.17em}=\hspace{0.17em}560\hspace{0.17em}}\mathrm{oe}\hspace{0.17em}\mathrm{for}\hspace{0.17em}\mathrm{iron})$ for the coercive force resulting from magnetocrystalline anisotropy. In addition, conspicuous growth defects on the surface are observed to be sites of easy nucleation. A field of about one oersted, if applied to the damaged end of an iron whisker of this size, suffices to reverse the magnetization by domain wall motion.