Modification of Co/Pt multilayers by gallium irradiation—Part 2: The effect of patterning using a highly focused ion beam

Abstract

The local and collective behavior of magnetic arrays fabricated by focused ion beam (FIB) patterning of a Co/Pt multilayer is described. The arrays comprised 1 μm nonirradiated square elements separated by narrow lines which were written using the FIB. While the square elements supported perpendicular magnetization, the ion fluence used to write the lines was chosen to make the local magnetization there lie in-plane. Lorentz microscopy showed that lines were approximately 60 nm wide and that the magnetization had the expected orientation. Application of fields perpendicular and parallel to the array showed that the magnetization in the square elements and in the lines could be controlled essentially independently of each other. Magneto-optic microscopy was used to study the behavior of the arrays as a whole. Frustrated checkerboard patterns were observed, whose detailed properties depended to an extent on the fluence used to write the lines.