Patterning of granular magnetic media with a focused ion beam to produce single-domain islands at >140 Gbit/in2

We have used a focused ion beam to directly pattern thin-film granular perpendicular Co₇₀Cr₁₈Pt₁₂ media. By cutting trenches ~6 nm deep in the ~20 nm media, we have produced square arrays of magnetically isolated islands with periods in the range 65-500 nm. At periods below ~130 nm we observe only single magnetic domains, which exhibit a rough “checker-board” pattern upon ac demagnetization. We have patterned at densities of over 140 Gbit/in²