Influence on the Recording Performance due to exchange coupling field of Soft Underlayer in Perpendicular Recording Media

抄録

  CoPt-TiO₂ granular-type media with extremely thin Ru intermediate layer were prepared on a highly oiiented high-B_s FeCo soft underlayer (SUL) pinned by an IrMn antiferromagnetic layer. Although the increase of the IrMn antiferromagnetic layer thickness deteriorates the crystal orientation of the media, the magnetic properties of the recording layer were little changed. On the other hand, the H_ch (H_c in the hard axis direction) of the SUL were greatly decreased and the H_ex (exchange coupling field) of the SUL was largely increased. The H_ex of about 10 Oe is effective for the magnetic domain control of the SUL. The recording performance was measured by using a SPT head. The S/N increased as the IrMn layer thickness was increased. This improvement of the recording performance seems to be responsible for the magnetic domain control by the IrMn antiferromagnetic layer. Moreover, enough effect was obtained by H_ex of about 10 Oe under environment of conventional spin stand measurement system.