Magnetic Study Of Two-dimensional Cr₃Te₄ Nanosheets

In recent years,the magnetic properties of two-dimensional（2D）ultra-thin intrinsic magnetic materials can be well regulated by external factors（such as electric field,stress,doping,etc.）,and may have some peculiar physical effects.At the same time,the heterojunction based on 2D magnetic materials is expected to be fabricated into spintronic devices with high spin injection efficiency due to the van der Waals interlayer contact interface,which has aroused great interest of researchers.So far,the chemical vapor deposition（CVD）method is considered a reliable method for manufacturing ultra-thin 2D materials due to its controllable layer thickness and high yield.In recent years,several 2D ultra-thin magnetic materials with excellent performance have been successfully synthesized by the CVD method,and there are still some high-performance 2D magnetic materials to be studied.Among them,the tetrachromium telluride（Cr₃Te₄）bulk material has an ultra-high Curie temperature,but the corresponding 2D Cr₃Te₄ nanosheets have not been synthesized.In view of this,the main content of this article is as follows:（1）Synthesis and characterization of Cr₃Te₄ nanosheets.In this thesis,chromium chloride powder and tellurium powder were used as the reaction source,and 2D Cr₃Te₄ nanosheets were prepared by controlling the temperature,carrier gas flow,and the amount of tellurium powder.The effects of different growth conditions on the morphology,size and thickness of Cr₃Te₄ nanosheets are discussed.Through a series of basic material characterization methods,it is proved that the nanosheets prepared by this method are hexagonal Cr₃Te₄ nanosheets with high crystalline quality,which can prove that our CVD method has good feasibility.By optimizing the experimental conditions,the thickness of this material can be adjusted to 1.2 nm.（2）Study on the magnetic properties of tetra-telluride trichromium Cr₃Te₄nanosheets.The magnetic susceptibility of Cr₃Te₄ nanosheets was tested using the vibrating sample magnetometer（VSM）in the comprehensive physical property testing system（PPMS）.Reflected magnetic circular dichroism spectroscopy（RMCD）was used to test the magnetic properties of a single Cr₃Te₄ nanosheet at different temperatures,which showed that it has magnetic anisotropy and thickness-dependent Curie temperature.Electron beam exposure and thermal evaporation were used to prepare the Cr₃Te₄nanosheets into Hall devices.The electromagnetic transport characteristics of the Cr₃Te₄ nanosheets were tested,and the abnormal Hall effect phenomenon was observed.Finally,the stability of the Hall device is studied.