Ru thickness (dRu) dependence of flopping field (Hf) was investigated in subnano-crystalline (Co100-xFex)88B12/Ru/(Co100-xFex)88B12 films with various Fe content, x. The Hf with dRu showed oscillatory behavior with the period of 1.5 nm of dRu, which was independent of the Fe content. The first peak of Hf takes the maximum value at x = 65 at.%, and the second peak was degenerated with increasing the Fe content. These results are analyzed in terms of interlayer coupling effect including the bilinear (J1) and biquadratic (J2) coupling energy. As the dRu decreases, the J1 oscillates and J2 monotonously increases. Although the J2 effect appeared at thinner dRu, i.e., dRu <0.7 nm, the J1effect was rather stronger than the J2 one. The magnitude of the first peak of J1was greatly enhanced with increasing Fe content, and took the maximum at x = 65 at.%. Therefore, a smooth interface was established in subnano-crystalline FeCoB, and the intrinsic strong J1was realized in FeCoB/Ru/FeCoB system even in ultrathin dRu of 0.3 nm.
- Interlayer coupling
- perpendicular recording medium
- soft magnetic underlayer
- subnano-crystalline FeCoB
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Electrical and Electronic Engineering