Influence of Ru/Ru–SiO2 underlayers on the microstructure and magnetic properties of CoPt–SiO2 perpendicular recording media

SiO2 was doped into Ru underlayer to reduce the grain size of CoPt–SiO2 perpendicular media. The effects of SiO2 volume fraction and sputtering deposition pressure of Ru–SiO2 underlayer on the microstructure and magnetic properties of CoPt–SiO2 media were studied. Increasing SiO2 volume fraction in Ru–SiO2 layer decreased the grain sizes of Ru and CoPt. Adding 5% SiO2 to Ru–SiO2 layer increased the coercivity and enhanced the exchange decoupling and thermal stability of CoPt–SiO2 layer. A further increase in SiO2 volume fraction caused the deterioration of magnetic properties of CoPt–SiO2 layer. Deposition of Ru–SiO2 layer at 1.3 Pa resulted in a smaller activation volume and higher thermal stability of the CoPt–SiO2 media than that deposited at 0.4 Pa.