Nucleation-type magnetization behavior in FePt (001) particulate films

Nucleation-type magnetization behavior is reported in sputtered FePt (001) films with an island structure, where the particles show a multiple-domain structure. A large coercivity H-C of more than 50 kOe is achieved at an initial applied field of only 6 kOe. The magnetization behavior and the magnetic domain observation indicate clearly that domain walls are wiped out completely at a low applied field, and once domain walls are wiped out, it is hard to nucleate reversed domains in the particles, resulting in high H-C. The remarkable nucleation-type behavior of magnetization is also found to give rise to anomalous minor loops when the applied magnetic field is alternated around zero and increased gradually. (c) 2006 American Institute of Physics.