Double recording layers stacked on a Ru spacing layer are commonly used to obtain good recording properties for antiferromagnetically coupled (AFC) longitudinal media. In this paper, we report on a study that clarified the role of the bottom recording layer (BRL). We measured physical magnetic properties such as magnetic anisotropy field (Hk), magnetocrystalline anisotropy energy (Ku), intergranular interaction, and thermal agitation of the AFC media, with and without BRL. Results showed that: 1) even a thin BRL (1 nm thick) significantly increases remanent coercivity Hcr; 2) this increase in Hk is mainly caused by an increase in Hk due to elimination of the low Ku region at the bottom portion of the top recording layer; and 3) judging from magnetic cluster size, insertion of a BRL can reduce the intergranular exchange coupling at the initial growth region of the recording layer.
- Double recording layer
- Intergranular exchange coupling
- Magnetic anisotropy field
- Remanent coercivity