MFM analysis of the magnetization process in L10–A1 FePt patterned film fabricated by ion irradiation

Ga+ ions at a dose of 0.1 at.% (1.5 × 1014 ions cm−2) were irradiated by focused ion beam (FIB) onto L10 FePt films with a [0 0 1] crystalline texture normal to the film plane, and two-dimensional patterns composed of squares with high-coercivity (L10 structure, 300 × 300 nm2 and 100 × 100 nm2) separated by a soft magnetic region (A1 structure) 100 nm wide were fabricated. The magnetic domain structure of patterned film was observed by in-field magnetic force microscopy (MFM). In the remanent state, the domain with magnetization normal to the film surface was observed in the central part of the L10 square, while the narrow domain with reversed magnetization is at the circumference of the square. The magnetization process is discussed based on the MFM observations.