Sub-50 nm planar magnetic nanostructures fabricated by ion irradiation

He+ ion irradiation of Co-Pt multilayers through a silica mask obtained by a combination of high resolution lithography and reactive ion etching can p roduce an optical contrast-free, entirely planar, sub-50 nm magnetically pa tterned array. Furthermore, the specificity of magnetization reversal in su ch arrays leads to a weak dispersion of coercive forces. The technique hold s promise for both present hard disk technology and future near field magne to-optical recording. (C) 1999 American Institute of Physics. [S0003-6951(9 9)01322-4].