Magnetic domain observations of FePt and CoPt particles fabricated by IBICVD

Abstract

FePt and CoPt particles were successfully fabricated by ion beam induced chemical vapor deposition (IBICVD) with a focused ion beam (FIB) system. The as-deposited FePt particles are amorphous, while the CoPt particles are crystallized in fcc structure. After annealed at 600°C for 1 hour in high vacuum chamber, the FePt particles are crystallized in fcc structure, and the crystallization structure of CoPt particles is improved. Magnetic force microscopy (MFM) was used to study the magnetic domain patterns of FePt and CoPt particles. Concentric domain pattern was observed in the as-deposited and annealed FePt particles. For the as-deposited CoPt particles, no magnetic domain pattern was observed. For the annealed CoPt particles, after applying 20 kOe magnetic field perpendicular to the substrate plane, the particles also show the concentric magnetic domains. It is suggested that the in-plane component of the magnetization will follow the circular boundary of the particles, which results in a circular domain structure. The observed concentric domain pattern is due to the alternately up and down, out-of-plane components.