Studies On Microstructures And Magnetic Properties Of Cu/CoCrPt/Cu Thin Films

Recently,the research about the nano-metal thin films which have ferromagnetic order,have received considerable attention in nanomagnetism. CoCrPt thin films with the hexagonal-close-packed(hcp) structure embedded in non-magnetic materials have been studied extensively,for their potential applications.In this study,Cu/CoCrPt/Cu with pseudo sandwich structure nano films were prepared by a DC facing target magnetron and RF sputtering system. We characterized the texture and surface morphology of the samples by XRD with Cu Kαand a multimode SPM.Magnetic properties of nanocomposite films were measured using a VSM.The main findings are obtained as follows:1.Keep the magnetic layer and the buffer unchanged,Cu(t=1,4,6,8, 10 nm) /CoCrPt(30 nm) /Cu(2 nm) with pseudo sandwich structure nano films were prepared by a DC facing target magnetron and RF sputtering system.We found that the Cu overlayer thicknesses have a great impact on microstructure and magnetic properties of the samples.The suitable thickness Cu overlayer thickness is improved the grain size to fine and distributed homogeneously and the smoothness of the film surface.VSM measurements indicate that the samples show perpendicular magnetic anisotropy,and to some extent,the out-of-plane coercivity is increases with the overlayer thickness increasing.It is considered as the contribution of shape anisotropy.In addition,the magnetic domain images indicate that underlayer thickness result in column magnetic domains.2.Keep the overlayer and the buffer layer unchanged,Cu(8 nm)/ CoCrPt(t =15,20,25,30,35 nm)/ Cu(2 nm) with pseudo sandwich structure nano films were prepared by a DC facing target magnetron and RF sputtering system, subsequently annealed in situ at 350℃for 30 min.VSM measurements indicate that the samples show perpendicular magnetic anisotropy,the out-of-plane coercivity is increases with the magnetic layer thickness increasing. It can mainly be attributed to aspect ratio increasing with magnetic layer thinness increasing.The origin of saturation magnetization increasing with magnetic layer thinness increasing is the percent of nonmagnetic atoms decreasing with magnetic layer thinness increasing.3.It has been found that the microstructure and magnetic properties of Cu (8nm)/ CoCrPt(35nm)/ Cu(2nm) films depend strongly on the post annealing temperature.Annealed at 550℃for 30 min,the coercivity reaches the maximum. At this time,Cu underlayer is island-like distribution on glass substrate.The pattern gaps between of islands result that the CoCrPt films grow into cylindrical granular films.In addition,because the overlayer atoms diffused into the magnetic layer in annealing process,the coercivity is enhanced.4.Cu(8nm) /CoCrPt(12.5 nm) /Cu(t nm) /CoCrPt(12.5 nm) /Cu(2 nm) films have been prepared by an RF sputter and DC facing-target sputter deposition mode.Insert layer Cu thickness is changed for t=1,2,3,4nm.Insert layer Cu can further separate the cylindrical granular CoCrPt films.The results indicated that suitable insert layer thickness can effectively separate the magnetic particles and optimize the magnetic domain structure.