Domain Observation And Manipulation In Quasi-two-dimensional Ferromagnet Cr₅te₈

Magnetic materials are widely used in the field of information storage.With the development of the information age,high-density memory devices are increasingly highlighting their application value,and understanding the magnetic material magnetization flipping behavior is the basis for realizing magnetic memory devices.There are microscopic magnetization units,magnetic domains,inside/on the surface of the ferromagnetic material,which is generated to satisfy the minimum condition of the total energy in the ferromagnet.The directions of atomic magnetic moments in the magnetic domains are the same,and the directions of atomic magnetic moments in different magnetic domains are different.Studying the magnetic domains of ferromagnetic materials is of great significance for understanding the magnetization reversal behavior of materials.Two-dimensional?2D?van der Waals?vd W?materials have the characteristics of ultrathin,flexible,etc.,and have rich characteristics in force,heat,electricity,optical,and magnetism.2D vd W magnets exhibit inherent ferromagnetic/antiferromagnetic ground states at specific temperatures?up to the atomic layer thickness?.The emergence of such materials opens up new areas of materials science and provides unprecedented opportunities for the development of spintronics.The magneto-optical Kerr effect?MOKE?is very sensitive to the magnetic properties of materials.Micro-MOKE technology is a non-destructive,non-contact,simple and convenient magnetic detection scheme,and has a high spatial resolution,can achieve micro-zone measurement.In recent years,under the hot spot of two-dimensional magnetic materials,micro-MOKE technology has also played an important role at the same time.The use of micro-MOKE technology to study the magnetic domains of two-dimensional magnetic materials and their evolution with magnetic fields provides a microscopic foundation for understanding and controlling the magnetic domains of materials.The main contents of this paper are as follows:?1?The macroscopic theory and microscopic origin of the magneto-optic Kerr effect are introduced in detail.The construction,testing principle,function and selection of various components,test procedures and data processing methods of the wide-field microscopic MOKE experimental system are systematically described.The system has good stability and can achieve a spatial resolution of?1?m.It can achieve a variable temperature and field,observe and record the magnetic domain structure of the out-of-plane magnetization direction in real time,and study the magnetic domain structure and evolution of the sample.?2?Using wide-field microscopic MOKE imaging technology,the quasi-two-dimensional ferromagnetic Cr₅Te₈ magnetic domain structure and its evolution with magnetic field were observed.It is found that the macro magnetic domain morphology is closely related to the crystal structure,which means that the in-plane magnetic exchange energy anisotropy is large in the quasi 2D crystal.Moreover,the surface defects of the sample will interfere with the free growth of the magnetic domain structure and modify the surface magnetic domain structure,thereby hindering or guiding the growth of the magnetic domain.?3?Relevant work on quasi two-dimensional ferromagnetic Cr₅Te₈ magnetic domain electrical manipulation has been carried out.