A core-shell type exchange-coupled composite (ECC) structure is developed with an L10 phase FePt core and an Fe shell. Coercivity decreases from 30.6 kOe for the FePt granular film with a very thin thickness of 3.2 nm, to 7.85 kOe for the FePt/Fe core-shell type granular film with a 3-nm-thick Fe. The energy barriers of the FePt/Fe films are measured by using Sharrock equation. A modified formula of gain factor considering the effect of films' thickness is proposed. Core-shell type FePt/Fe ECC granular film has a large advantage over a conventional granular film for media application.
Bibliographical noteFunding Information:
This work was supported in part by Western Digital through the membership of the Center for Micromagnetics and Information Technologies (MINT) and in part by the Information Storage Industry Consortium (INSIC). The authors thank Dr. K. Srinivasan and G. Berteroand from WDC and Dr. T. Rahman from the University of Minnesota. The NSF MRSEC and Characterization Facility, Institute of Rock Magnetism Facilities and Department of Chemical Engineering & Materials Science, are gratefully acknowledged for structural and magnetic measurements.
- Core-shell structure
- ECC media
- Gain factor
- L1 FePt