Study On Controlling Phase Constituents And Magnetic Anisotropy Of SmCo-based Films Based On External Field Induction

With the development of science and technology and manufacturing level,magnetic materials and devices are widely used in many fields such as national defense technology,aerospace,micro-electromechanical systems,and information storage.As a high-performance rare earth permanent magnetic material,SmCo is an ideal candidate material for non-volatile thermally assisted magnetic recording media.It is deposited on the components in the form of thin films to provide a strong local magnetic field and can also meet the requirements of integration and miniaturization of magnetic functional devices.However,SmCo-based films have problems such as complex phase composition and difficult transformation of magnetic anisotropy,which is not conducive to the wide application of magnetic functional devices.Based on this,this paper introduces an external field(temperature gradient field and applied magnetic field)to control the phase composition and magnetic anisotropy of the SmCo-based thin film.First,this paper studies and optimizes the process parameters of SmCo-based thin films prepared by magnetron sputtering.Under 80W DC sputtering power and 0.5 Pa deposition pressure,the SmCo deposition rate is 14 nm/min,and then the thickness of the SmCo magnetic layer is adjusted according to the deposition rate.It is found that the film has the best magnetic properties and smaller grain size when the thickness is 280 nm;Cu atoms are doped and thermally diffused,at this time,the film has two phases of SmCo₅and Sm₂Co₁₇coexist,and the out-of-plane coercivity is increased to 1580 Oe.Secondly,the influence of the vacuum tube furnace conventional thermal annealing(CTA)process and the temperature gradient field generated by the infrared rapid thermal annealing(RTA)on the SmCo-based thin film magnetic anisotropy was studied.It is found that when the CTA process is kept at 550?for 15 min,the crystalline quality of the film is better and the degree of oxidation is weaker,the particle size of the film surface is smaller,and the in-plane and out-of-plane coercivity are 10500 Oe and 1670 Oe respectively;At the same heat treatment temperature and holding time,the coercivity of the film samples treated by RTA process is increased to 2810 Oe at the heating rate of 20?/s,the diffraction peak intensity of SmCo₅(200)and Sm₂Co₁₇(300)decreases,and the in-plane anisotropy decreases.At the same time,the roughness and grain size of the thin film samples are smaller,and the contrast between the light and dark of the magnetic domain is large,indicating that the perpendicular magnetic anisotropy is improved at this time.Finally,SmCo film deposition was assisted by adding Nd Fe B magnets to provide a magnetic field perpendicular to the film surface.When the size of the magnet is 18*18*24 mm,the magnetic field intensity is 2300 Oe,and the deposition rate of the SmCo layer increases to18 nm/min.The out-of-plane coercivity of the SmCo-based alloy films deposited by the external magnetic field and treated with RTA increased to 3400 Oe,and the grain size is refined.Compared with the samples without external magnetic field assisted deposition,the XRD pattern showed that the characteristic diffraction peaks of SmCo₅(200)and Sm₂Co₁₇(300)with in-plane orientation disappeared,and the magnetic anisotropy was changed preliminarily.