Development Of A Vertical Magnetization Writing Instrument With Micrometer Resolution

Many theories beyond the standard model usually predict that there may be new interactions at short range.Our group are performing experimental test of the spindependent new interactions mediated by axion-like particles at the micrometer range.Since the interaction to be tested is proportional to(?)·(?)),we propose to use a magnetic structure with periodic modulation of electron spin polarization perpendicular to the surface.The magnetic structure is composed of magnetic nanopillar arrays.How to control the magnetization of the nanopillar arrays is the key issue of this experiment,and the research of this thesis is to develop a magnetization writing instrument with micrometer resolution,which is used to locally magnetize the magnetic structure and prepare the magnetic structure with periodic modulation of the spin polarization direction.The magnetization writing instrument developed in this thesis uses a magnetic tip to apply a magnetic field locally,and thus to realize the spin orientation control of the magnetic nanopillar arrays.First,the spatial distribution of the magnetic field generated by the tip are evaluated using finite element simulation.The magnetization writing resolution is analyzed for different gaps between the tip and the magnetic core below,and for different tip radius of curvature.The simulation shows that the resolution of magnetization writing can be slightly improved with the decrease of gap,and can be improved when the tip radius of curvature is reduced.When the gap is 4.5 mm,the resolution of the magnetic tip with a radius of 1 ?m is 7.68 ?m.Second,we fabricate the magnetization writing tip by electrochemical etching method,and investigate the influence of the concentration of HCl solution on the quality of the magnetization writing tip.The smallest radius of curvature achieved is about 4.05 ?m.Finally,the magnetization writing instrument was built and tested,and the control program was written based on Lab View.The program can perform instrumental parameter setting,distance feedback control between the tip and sample,sample auto-approach,sample stepping near and away from the tip,setting of the distance and lateral position between the tip and sample,and scanning magnetization.The instrument will been used for the preparation of magnetic structures in experimental test of the spindependent interactions.