Space and thickness influence on magnetization reversal in periodic cylinder shaped exchange spring

• Coercive field increases with the increase of space between periodic cylinders.
• Critical field of magnetization reversal decreases with the increase of thickness in soft layer Fe3Pt.
• Magnetization in central region starts to reverse first in periodic cylinder Fe3Pt/FePt exchange spring.

Magnetization reversal in periodic cylinder shaped exchange spring with soft layer Fe3Pt and hard layer FePt has been studied. Coercive field increases with the increase of space between periodic cylinders due to dipole effect in exchange spring Fe3Pt/FePt. Critical field of magnetization reversal decreases with the increase of thickness in soft layer in Fe3Pt/FePt system. This phenomenon is caused by the competition between exchange coupling effect and demagnetization effect. Moreover, from the status of magnetization in different field, magnetization in central region of the periodic cylinders starts to reverse first in periodic cylinder Fe3Pt/FePt exchange spring. The reversion of magnetization from center to boundary is caused by the competition between demagnetization field and magnetic field in periodic cylinder exchange spring.