Microstructure and magnetic properties of CoPt-SiNx/Ag thin films

Different amounts of amorphous SiNx nonmagnetic material and magnetic Co50Pt50 alloy were cosputtered on the different thicknesses of Ag films at room temperature then annealed at different temperatures. When the thickness of Ag underlayer is 25 nm, the CoPt/Ag film has a minimum in-plane squareness (S-parallel to) which is about 0.35. The out-of-plane squareness (S-perpendicular to), out- of-plane coercivity (H-c perpendicular to), and saturated magnetization (M-s) values of the CoPt/Ag (25 nm) film are about 0.95, 15 kOe, and 420 emu/cm(3), respectively. From the microstructure analysis of CoPt-SiNx/Ag (25 nm) films with different volume percent of SiNx content, it is found that the average grain size of CoPt decreases from about 80 to 9 nm when the volume percent of SiNx is increased from 0% to 50%. The S-perpendicular to, H-c perpendicular to, and M-s values of the (CoPt)(50)-(SiNx)(50)/Ag films are about 0.5, 7.5 kOe, and 200 emu/cm(3), respectively. (C) 2008 American Institute of Physics.