Large enhancement of coercivity of magnetic Co/Pt nanodots with perpendicular anisotropy

Nanodots consisting of Co/Pt multilayer have been fabricated using nanosphere lithography and ion beam etching. The nanodots retained the perpendicular anisotropy as that of the continuous films. However, the coercivity of the nanodots was greatly enhanced, more substantially for smaller nanodots. Concurrently, the remnant magnetization was reduced to 50%-80%. Magnetic force microscopy revealed that the domain pattern of nanodots at the remnant state was largely single domain but with nonperpendicular stray fields on the edges, indicating noncollinear alignment of magnetizations in those regions. (C) 2007 American Institute of Physics.