High coercivity and small grains of FePt films annealed in high magnetic fields

摘要

The coercivity and grain size of equiatomic FePt alloy films annealed at 500 and 600 degrees C with different magnetic fields of 0-70 kOe have been investigated. It is found that applying a magnetic field with appropriate strength during postdeposition annealing not only enhances the coercivity but also reduces the grain size of the FePt films. Measurements of the microstructure and magnetic properties of the FePt films reveal that the coercivity is affected by both the ordered volume fraction and a microstructure factor that is related to the ordered volume fraction. The high coercivity in FePt films annealed with an appropriate strength of magnetic field is due to an increasing density of magnetic domain wall pinning sites concurrent with an increasing fraction of the ordered phase.