Lorentz transmission electron microscopy of focused ion beam patterned magnetic antidot arrays

A focused-ion beam has been used to pattern magnetic antidot arrays containing different sized antidots and spacings in ${\mathrm{Ni}}_{\mathrm{80}}{\mathrm{Fe}}_{\mathrm{20}}$ films. Their magnetic domain structure has been studied using Lorentz transmission electron microscopy, which has shown that the edges of the antidots pin the domain walls during magnetization reversal. The remanent domain structure was found to depend strongly on the antidot size and spacing, from domains pinned between the corners of adjacent rows of antidots for large sizes to domains pinned between the edges of adjacent antidots for small sizes. The relevance of such structures for high density recording is discussed.