Multielement And Multiphase Magnetic Composite Nanowires Prepared By DC Electrochemical Deposition

With the advent of the electronic information age,the demand for efficient magnetic storage technology is increasingly strong.One-dimensional nanowire is a typical perpendicular magnetic recording technology with high shape anisotropy,which can effectively improve the recording density and is a hot topic in the development of magnetic recording technology.In this paper,Tb-Fe-Co magnetic nanowires were prepared by direct current chemical deposition using AAO(anodic alumina)template.On this basis,Tb-Dy-Fe-Co magnetic nanowires were prepared by continuous deposition with adding Dy element to the deposition solution.In addition,Tb-Fe-Co deposition solution and Sm-Co deposition solution are alternately deposited to successfully prepare Tb-Fe-Co/Sm-Co multi-phase nanowires.The microscopic morphology,composition,phase structure and magnetic properties of the nanowires are characterized by XRD,EDS,SEM,TEM and VSM.Analysis of XRD patterns shows that the as-deposited Tb-Fe-Co nanowire consists of Fe Co phase.After annealing at 600?for 3 h,Tb element dissolved in Fe Co phase forms Fe₃Tb phase,Fe₂Tb phase,Co₃Tb phase and Co₁₇Tb₂phase with Fe and Co elements.The as-deposited Tb-Dy-Fe-Co nanowire and the as-deposited Tb-Fe-Co/Sm-Co nanowire only have Fe Co crystalline phase and amorphous phase.After annealing at 600?for 3 h,the amorphous phase is crystallized.The annealed Tb-Dy-Fe-Co nanowire consists of Fe₃Tb phase,Co₁₇Dy₂phase,Co₃Dy phase and Dy Fe₅phase.The annealed Tb-Fe-Co/Sm-Co nanowire forms Co₁₇Tb₂phase,Fe₁₂Sm phase,Co₂Sm₅phase,Sm₂Co₁₇phase and other crystalline phases.The phase composition of the three nanowires obtained from the HRTEM images by FFT is consistent with XRD patterns analysis.In the microstructure of Tb-Fe-Co magnetic nanowires,it is found that Fe₃Tb phase and Co₃Tb phase have a coherent phase boundary.In the analysis of Tb-Dy-Fe-Co,Tb-Fe-Co/Sm-Co nanowires,it is found that different phases are distributed like steps.This discovery reveals the key reason why electrochemical methods can successfully deposit rare earth doped nanowires is the induced co-deposition,which provides a theoretical basis for further exploration of the preparation of rare earth alloy nanowires in the future.By comparing the magnetic properties of Tb-Fe-Co nanowires,Tb-Dy-Fe-Co nanowires and Tb-Fe-Co/Sm-Co nanowires with different Tb³⁺concentrations,it is found that the magnetic properties of Tb-Dy-Fe-Co nanowires and Tb-Fe-Co/Sm-Co nanowires are both better than those of Tb-Fe-Co nanowires.At the same time,the effect of coherent phase boundary on magnetic properties is explained by pinning effect in Tb-Fe-Co nanowires.When the concentration of Tb³⁺is 0.04 mol/L,the annealed Tb-Dy-Fe-Co nanowires has the best performance.Coercive force is2664.60 Oe and remanence ratio is 0.5.When the concentration of Tb³⁺is 0.04 mol/L,the coercivity of Tb-Fe-Co/Sm-Co nanowires after annealing is 2956.25 Oe and the remanence ratio is 0.88.This discovery opens up the development field of perpendicular magnetic recording materials,and more excellent perpendicular magnetic recording materials can be obtained through interaction of different rare earth elements or bidirectional coupling of soft and hard magnetic phases.