Influence of synthetic nucleation layers on the microstructure, magnetic properties, and recording performance of CoCrPt–SiO₂ perpendicular recording media

The performance of CoCrPt–SiO₂ perpendicular recording media, which incorporate synthetic nucleation layers for inducing grain size control, was evaluated with regard to the crystallographic, microstructural, magnetic, interfacial, and recording properties. The media structure consisted of a 14 nm thick CoCrPt–SiO₂ recording layer sputtered on two stacked Ru intermediate layers. When a submonolayer thick synthetic nucleation layer was inserted between the two Ru intermediate layers, the grain size and grain size dispersion were significantly reduced in both the upper Ru layer and the recording layer. An average grain size of 5.8 nm with 20% dispersion was achieved for the recording layer. The crystallographic growth of the Co (00·2) perpendicular texture remained unaffected with the Δθ₅₀ at ∼4.4°; the coercivity was ∼2800 Oe and the coercivity squareness was ∼0.6. The roughness of the interface between the synthetic nucleation layer and the upper Ru intermediate layer did not significantly change, and the surface roughness was also relatively unchanged at ∼2.5 Å. An improvement in the signal-to-noise ratio by 1.5 dB was observed due to the synthetic nucleation layer. The effectiveness of the synthetic nucleation layer approach toward achieving grain size control and improving the performance of the CoCrPt–SiO₂ perpendicular recording media is demonstrated.