STUDY OF LARGE-AREA HIGH-DENSITY MAGNETIC DOT ARRAYS FABRICATED USINGSYNCHROTRON-RADIATION BASED X-RAY-LITHOGRAPHY

Large area arrays of dots have been patterned in Au/Co/Au(lll) sandwic hes with ultrathin Co layers (0.6 to 2 nm) and a perpendicular easy ma gnetization axis. Dot dimensions down to 0.2 mu m have been achieved u sing x-ray lithography, with either positive resist and direct ion bea m etching or a lift-off process with aluminum mask. Both processes hav e been tested against the damages they induce to the fragile structure of the samples. The magneto-optical effects and magnetization reversa l processes in the arrays have been characterized versus Co thickness, dot dimension, and lattice aspect ratio. For high quality samples, th e domain walls propagation mechanism that drives magnetization reversa l in as-grown films is drastically modified in dot arrays, leading to a large increase of the coercive field with dot diameter reduction, to gether with changes in the shape of the hysteresis loops. (C) 1995 Ame rican Vacuum Society.