Exchange coupled composite (ECC) media consisting of both magnetically hard and soft regions within the same grain have been proposed for 1 Tb/in 2 perpendicular magnetic recording. Compared to conventional perpendicular media, a composite structure can effectively decrease the switching field of the media without a loss in thermal stability. This paper reviews the recent work on composite media including two spin and complete micromagnetic models for ECC media, exchange spring media, synthetic antiferromagnet ECC media, and experimental results in support of these theories. The figure of merit (defined as ξ= 2E/(MSH SV), where ΔE, MS, HS, and V are energy barrier, saturation magnetization, switching field, and grain volume of the media, respectively) of composite media is found to be 2 ∼ 3 times that of conventional media. Therefore, grain volume can be decreased and the impact of the magnetic recording "trilemma" reduced. The switching mechanism of composite media is discussed and Its properties such as angular dependence of switching field and thermal attempt frequency is studied and compared with conventional media. Results for micromagnetic simulation of recording on ECC media are shown together with a brief discussion of write head design for ECC media.
Bibliographical noteFunding Information:
Manuscript received September 21, 2007; revised March 4, 2008. Current version published December 2, 2008. This work was supported in part by the IGERT program of the National Science Foundation under Award DGE-0114372, the National Science Foundation under Award ECS-0300209, the INSIC EHDR program, and Seagate Technology. The authors are with the Department of Electrical Engineering, Center for Micromagnetics and Information Technology, University of Minnesota, Minneapolis, MN 55455 USA (e-mail: email@example.com; firstname.lastname@example.org).
- Composite media
- Exchange coupled composite media
- Exchange spring media
- Perpendicular magnetic recording