Density modulation of magnetic skyrmions in Pt/Co/Au multilayers
Magnetic skyrmion has a topological spin texture,which possesses many excellent features such as small size,stable structure and low drive current density.It has great potential application in information storage and information processing.Ferromagnetic multilayer films with interfacial DMI can be compatible with modern nanocrystalline manufacturing processes in the material system with magnetic skyrmions.Magnetic skyrmions generated in the ferromagnetic multilayer films can be stable at room temperature,which is important for developing electronic devices based on magnetic skyrmions.However,due to the competing interfacial DM interactions,magnetic anisotropy,exchange interactions and dipole interactions in magnetic multilayers,the generation of magnetic skyrmions lacks regularity and has a low density.The systematic tuning of material parameters to generate high density magnetic skyrmions at room temperature in magnetic multilayers is the key step to solve this problem.Here,a series of Pt/Co/Au multilayers with different Co layer thicknesses were prepared by magnetron sputtering.Their magnetic anisotropy was qualitatively analyzed using hysteresis lines obtained from a vibrating sample magnetometer(VSM).Their magnetic domain structure was imaged using the Lorentzian mode of transmission electron microscopy.The result showed that the density of magnetic skyrmions increased and then decreased as the Co layer thickness increases,with the maximum density of magnetic skyrmions at a Co layer of 2.1 nm.Theoretical calculations showed that the change in the thickness of the magnetic layer caused a shift in the magnetic anisotropy and a change in the endogenous property Dzyaloshinskii-Moriya interaction D,which in turn affected the change in the magnetic skyrmions density.
magnetic skyrmionsspherical electron microscopyLorentz techniquemagnet layer thickness
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