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

The local and collective behavior of magnetic arrays fabricated by focused ion beam (FIB) patterning of a Co/Pt multilayer is described. The arrays co mprised 1 mum nonirradiated square elements separated by narrow lines which were written using the FIB. While the square elements supported perpendicu lar magnetization, the ion fluence used to write the lines was chosen to ma ke the local magnetization there lie in-plane. Lorentz microscopy showed th at lines were approximately 60 nm wide and that the magnetization had the e xpected orientation. Application of fields perpendicular and parallel to th e array showed that the magnetization in the square elements and in the lin es could be controlled essentially independently of each other. Magneto-opt ic microscopy was used to study the behavior of the arrays as a whole. Frus trated checkerboard patterns were observed, whose detailed properties depen ded to an extent on the fluence used to write the lines. (C) 2001 American Institute of Physics.