Research On Storage Medium And For Magnetically Induced Super Resolution And Blue Wavelength Magneto-optical Data Storage

Magneto-optical (MO) data storage, based on Kerr effect, is advantageous over both magnetic recording and optical storage. Magnetically induced super resolution(MSR) and blue wavelength are two kind of important technology to increase the density of MO data storage medium. In order to futher increase MO recording density, here we prpose to combine the advantages of blue wavelength and MSR in one storage system. This work is of great significance to improve the density of MO data storage.Both PtCo/TbFeCo and NdGdFeCo/TbFeCo exchange-coupled double-layers were prepared using direct current (DC) magnetron sputtering. The magnetic and MO properties of both single and double layers were tested using the surface magneto-optical Kerr effect (SMOKE) system, vibrating sample magnetometer(VSM), Kerr spectrum etc. The double layer exchange coupling effect of blue/MSR data storage was researched. And further research about the influence of sputtering conditions on properties of the single layer.Through the adjustments of the sputtering parameters, we fabricated TbFeCo films with perpendicular anisotropy and Pt₃Co, NdGdFeCo films with in-plane anisotropy. The best sputtering parameters are found to be: PtCo (80W, 3.0Pa, 300℃, 10nm), the property of Pt₃Co alloy film is T_c=160℃,H_c=100Oe; NdGdFeCo (60W,0.8Pa, RT, 50nm), the property of Nd₁₂Gd₂₃(Fe₇₅Co₂₅)₆₅ noncrystal alloy film is H_c=300Oe,θ_k=0.42°(λ=300nm),T_comp=90℃; TbFeCo (60W, 1.0Pa, RT, 50nm), theproperty of Tb₂₀(Fe₈₅Co₁₅)₈₀ noncrystal alloy film is H_c =3500Oe, T_comp < RT,T_c≈250℃. These properties indicated that the alloy films P₃tCo and NdGdFeCo can be used as readout layer for the blue wavelength and MSR data storage, and the alloy film TbFeCo can be used as recording layer for the storage.Based on the studies of single-layer PtCo/TbFeCo and NdGdFeCo/TbFeCo double layer films were prepared under the same conditions as those of single layers without breaking vacuum in the first time. For Pt₃Co/Tb₂₀(Fe₈₅Co₁₅)₈₀ film, when the temperature is 160℃, we find that the magnetization direction of Pt₃Co film changed to be out-of-plane. For Nd₁₂Gd₂₃(Fe₇₅Co₂₅)₆₅/Tb₂₀(Fe₈₅Co₁₅)₈₀ double layer films, this exchange coupling effect was observed at 90℃. At RT, the redout layer(Pt₃Co or NdGdFeCo) has in-plane magnetization, however, when the temperature rise to certain value,it has out-of-plane magnetization and copy the bit information of the recording layer. These two kinds of double layer films can both realize CAD-MSR (Center Aperture Detection Magnetically Induced Super Resolution) effect therefore they are suitable for MSR recording. Because Pt₃Co and NdGdFeCo have large Kerr effect under the blue wavelength MSR recording, both Pt₃Co/TbFeCo and NdGdFeCo/TbFeCo exchange coupled double layer can be used as blue wavelength and MSR MO data storage.