Research On Microstructure And Magnet Properties Of NdFeB/Co Multilayered Thin Films Prepared By Magnetron Sputtering

In this paper, the NdFeB single layers and NdFeB/Co multilayered films were prepared by magnetron sputtering. The deposition rate, surface morphology, microstructure and magnetic property of films were investigated by means of SEM, AFM, XRD, VSM, SQUID. And we studied the effect of the structure of multilayer and the annealing prosess on the microstrure and magnetic property of NdFeB/Co multilayer films.The experimental results show that deposition rate increases with the increase of sputtering power. The deposition rate firstly increases and then decreases with the increase of Ar working pressure. Film thickness was in the direct ratio to sputtering time. Deposition rate has important effect on surface morphology of the films. The as-fabricated films were amorphous. After annealing, the films transformed to crystalline, Nd₂Fe₁₄B and Co were in presence together in films. SEM and AFM observation indicated that the film is smooth and dense after annealing. Grain size increases with the annealing temperature. With optimal annealing technique, the multilayer films have excellent coercive force, remanence ratio and perpendicular magetic anisotropy.The analysis shows that the coercive force of the multilayer films decreases with increasing the thickness of Co layer. And coercive force increases with the increasing the thickness of NdFeB layer. When the thickness of Co layer was between 20～30nm, multilayer films has present excellent remanence ratio. The number of NdFeB/Co bilayer repeats does not affect magnetic property of multilayer films greatly.