Structural properties of CoPt films patterned using ion irradiation

Patterned CoPt films were fabricated using a combination of e-beam lithography and He⁺ ion irradiation to produce a planar array of ordered CoPt squares separated by disordered CoPt areas: (i) by molecular beam epitaxy was deposited a CoPt ordered film which corresponds to a “natural” multilayer: alternating pure cobalt and pure platinum (0 0 1) planes. (ii) The film was covered by a 300 nm thick Pt layer mask. (iii) Irradiation with appropriate ion beam and fluence disorders the CoPt film where not protected by the mask. X-ray diffraction, as well as atomic and magnetic force microscopy, is used to characterise the structural and magnetic changes in the film. The He⁺ ion irradiation does not significantly modify the surface of the CoPt film: the roughness almost remains identical (2 nm). This is promising for applications in magnetic recording technologies.