Effect of SiN $_{\rm x}$ Capping Layer on the Microstructure and Magnetic Properties of CoPt/Ag Thin Films

The magnetic properties and microstructure of the CoPt/Ag and SiN_x/CoPt/Ag thin films deposited by dc and rf magnetron sputtering on glass substrates were studied. When the Ag underlayer is introduced to the CoPt film then annealed at 700^degC, the CoPt/Ag film has large out-of-plane squareness (S_perp), out-of-plane coercivity (H_{c perp}) , and saturation magnetization(M_s), they are 0.96, 14 kOe, and 420 emu/cm³, respectively. After the SiN_x capping layer is added, it is found that the SiN_x capping layer would inhibit the CoPt (001) texture growth. The M_s value is increased due to the amount of fct CoPt phase is decreased and the inhibition of oxidation by the SiN _x capping layer. The X-ray peak intensity ratio of CoPt (001) and CoPt (111) planes ( I₀₀₁/I₁₁₁ ratio) were decreased after annealing as the SiN_x capping layer is added.