AVS 46th International Symposium
    Magnetic Interfaces and Nanostructures Technical Group Monday Sessions
       Session MI+VM+AS-MoA

Invited Paper MI+VM+AS-MoA5
Sub 50 nm Planar Magnetic Nanostructures Fabricated by Ion Irradiation

Monday, October 25, 1999, 3:20 pm, Room 618/619

Session: Magnetic Recording: Media and Heads
Presenter: C. Chappert, IEF/Université Paris Sud, France
Authors: T. Devolder, IEF/Université Paris Sud, France
C. Chappert, IEF/Université Paris Sud, France
Y. Chen, L2M Bagneux/CNRS, France
H. Bernas, CSNSM/Université Paris Sud, France
J.-P. Jamet, LPS/Université Paris Sud, France
J. Ferré, LPS/Université Paris Sud, France
E. Cambril, L2M Bagneux/CNRS, France
Correspondent: Click to Email
Areal density enhancement is a major challenge in magnetic recording. Near field magneto-optical techniques are one fast-developing attempt to respond. At bit density values above 65 Gbits/in@super 2@, a most drastic requirement will be to write stable bits with nanometer wall jaggedness, at very precise locations on the disk. Patterned media could be a promising response to this problem.@footnote 1@ However, surface roughness, and polarization dependent effects due to abrupt changes in optical index, will likely deteriorate the signal to noise ratio. Through interface mixing, light ion (He+) irradiation can modify in a precisely controlled way the magnetic properties of multilayers, with negligible change of surface roughness and optical indices. In (Co/Pt) multilayers with perpendicular easy magnetization axis, the anisotropy decreases with irradiation, which first reduces the coercive force, then induces in-plane magnetization. Patterning only the magnetic properties can then be obtained by irradiation through a lithographic PMMA resist mask.@footnote 2@ Using SiO@sub 2@ masks, we have fabricated regular arrays of such irradiation-patterned nanostructures with sizes down to 30 nm. Different configurations such as hard (resp. soft) nanostructures in soft (resp. hard) media have been obtained and characterized using far field magneto-optical microscopy. Special attention has been devoted to the study of the transition zone between irradiated and protected areas, and its effect on magnetization reversal. The technique may be a powerful tool for ultrahigh density magnetic recording applications. @FootnoteText@ @footnote 1@ S. Chou et al., Data Storage 35 (1995). @footnote 2@ C.Chappert et al., Science 280, 1919 (1998).