Research On Magnetic Microscopic Measurement Technology

Since graphene was successfully exfoliated,in order to meet the needs of 2D materials in practical applications,it is particularly important to understand and tune their magnetic and spin properties.However,when two-dimensional materials are exfoliated to a few layers or even a single layer,the size is basically in the order of micrometers,the size is limited,and the magnetism,whether intrinsic or extrinsic,is very weak.How to extract weak magnetic signals from small-sized samples has become a problem that researchers have to face.The magneto-optical imaging technology is often used in the magnetic research of magnetic materials due to its non-contact,non-damage,high-resolution,and high-precision characteristics.Magneto-optical imaging technology has developed rapidly in recent years,and has become an important means of visualizing magnetic domains and magnetization processes,and has been widely used in all walks of life.At the same time,the performance of magnetic components is closely related to the material magnetic moment distribution and its evolution process.From the perspective of science,applied physics and engineering,many important results have been obtained through magneto-optical imaging technology.Magneto-optical imaging is widely used in the study of magnetic anisotropy,magnetic order,phase transition behavior of interlayer coupling,functional materials and spin waves in magnetic thin film materials.Especially for the research of ultra-high density recording technology,magnetic imaging technology is essential.The magneto-optical Kerr method is a main method to measure the properties of magnetic materials,especially the magnetic properties of thin-film materials.As a common method in magnetic research,the magneto-optical Kerr effect has become an important tool to characterize magnetic thin-film materials.As a typical two-dimensional material,magnetic thin film materials have a wide range of applications in magnetic bubble and magnetic recording technology.Magneto-optical multilayer films have excellent recording properties and are regarded as important media materials for future magneto-optical recording.Multi-layer film materials are generally composed of alternating Co,Co-Ni,Pt or Pd,and the superposition of multi-layer dielectrics leads to high vertical anisotropy of these materials.The main research contents of this paper are as follows: Develop a measurement system based on the magneto-optical Kerr effect(Moke),realize two measurement modes,polar and longitudinal,use laser to irradiate the surface of the magneto-optical dielectric film,and receive photoelectric signals through a balanced photodetector,scan out the hysteresis loop of the magnetic sample,so that the information such as the coercive force of the thin film material can be quantitatively and qualitatively analyzed.According to the different direction of the magnetic moment in the magnetic film,the magnetic film can be divided into in-plane magnetic anisotropy film and perpendicular anisotropy film.Corresponding to the classification of thin film samples,two measurement methods of polar direction and longitudinal magneto-optical Kerr effect are designed respectively.Cobalt-based,permalloy and composite magnetic thin film materials are selected as the measurement objects,and the results are measured and analyzed.