Micromagnetism of two-dimensional permalloy particles with different aspect ratios

Micromagnetic properties of the Fe19Ni81 (5 nm)/NiO (50 nm)/Fe19Ni81 (30 nm) structured system have been investigated in a photoemission electron microscope in the magnetic X-ray circular dichroism operating mode. The microstructured Fe19Ni81 (5 nm) film contained two-dimensional islands with the aspect ratio varying from 1:1 to 10:1, and the linear size of their long axis comprised 24, 12 and 6 7m. It is shown that the magnetic domains have the direction of magnetization preferentially parallel and antiparallel to the magnetic field direction in which this system was prepared. Their number is determined by the particles' sizes, their shape as well as by the direction of the external magnetizing field and can be characterized by a non-monotonic size dependence. The magnetization of domains with different lateral sizes was found to be 0.4 T with an accuracy better than 20%.