Ultrathin exchange coupled composite (ECC) FePt granular recording media with different soft layer anisotropy were fabricated by controlling the soft layer deposition temperature. As the soft layer (FePt-SiO 2) deposition temperature (T Soft) increased, the overall FePt (001) texture of ECC FePt thin films was improved, while the saturation magnetization (Ms) and the thermal stability factor were also increased. The effect of soft layer anisotropy field on the coercivity (Hc) and the remanent coercivity (Hcr) of ECC FePt thin films showed a V shape relationship, with the minimums at T Soft of 200°C. These results are consistent with the theoretic predication based on domain wall assisted magnetization reversal mechanism. The ECC FePt thin film with T Soft of 200°C may have a gain factor larger than 2.
Bibliographical noteFunding Information:
This work was partially supported by Western Digital. Parts of this work were carried out in the Characterization Facility, University of Minnesota, a member of the NSF-funded Materials Research Facilities Network (www.mrfn.org) via the NSF MRSEC program under award number DMR-0819885. The authors thank the useful discussion with Dr. Hua Yuan, Dr. Kumar Srinivasan, Dr. Ramamurthy Acharya, and Dr. Gerardo Bertero.