Magnetic Properties Investigation Method Of Materials Under High Pressure

Diamond anvil cell (DAC) technology has great significance for the developmentof high-pressure physics in recent decades. Since DAC technology was first applied in1950, the static pressure has become another physical parameter which is simple andsafe to control in addition to temperature. This provides the researchers with aneffective and reliable means to obtain ultra-high static pressure on the sample whichneeds observations. This technology has undergone decades of development, and isconstantly improving. By combining DAC with other techniques, a variety of in situdetection of physical parameters under high pressure are emerging. These have greatlyexpanded the research scope of high-pressure physics.The study of magnetic properties of matter is directly related to the basic researchof its structure. Magnetism is not only a macroscopic physical parameter, but alsoclosely related to atomic structure, crystal structure and other aspects of microstructure.Therefore, the study of magnetic properties is one important way to study the internalstructure of the matter. A good knowledge of the impact of measurement pressure onthe magnetic properties of sample enables us to have a more intuitive and deepunderstanding. Through experiments, existing theories could be verified. We couldeven predict new phenomena that cannot be created under the current laboratoryconditions. In addition to high-pressure physics, the fields of geology, materials scienceand other related disciplines have made some theoretical predictions on the magnetismrule under pressure. There are also a huge number of experiments that use indirectobservations for the validation and analysis of the relevant theoretical work.It is certain that the development and application of measurement technologywould expand the research methods and research area of high-pressure physics. It couldbe of great importance to the research of relevant disciplines. Since Vodar B et almeasured the parameters such as magnetic susceptibility on DAC for the first time in1980, DAC-based magnetic measurement technology has been developing rapidly. A number of laboratories have already made some exploration in this direction. Relevanttechnologies are summed up and the corresponding experimental apparatuses andmethods have been developed. For example, the United States Naval ResearchLaboratory measured the superconducting transition temperature variation as a functionof pressure. Stuart A et al from the Institute of Earth Physics of Paris improved thedevice and experiment on this basis. The reversible magnetic signal of two naturalmagnetite samples under high pressure was observed. Institute of Physics of Academyof Science of China and Carnegie institution of Washington also developed their ownhigh-pressure magnetic measuring technology. The relevant experiments on magnetismof materials were carried out.Temperature is selected as the variable in most of the current high-pressuremagnetic measurement experiment. By plotting the diagram of material magnetismchanging with temperature under different pressures, the influence of pressure on themagnetic transition temperature Tc is discussed. In order to achieve a more directmeasurement, previous works are summarized and modified. A new set of test systemsand methods is designed. Direct observation of material’s magnetic signal variationunder pressure at constant temperature (room temperature) is realized. The new systemhas simplified the traditional measurement process. It is easily compatible with otherexisting means of measurement. Data are presented in a more intuitive way. Thepressure-induced magnetic transition of Fe sample at room temperature is successfullyobserved. The magnetic transition of Fe near13GPa has been confirmed. This verifiedthe correctness of the previous theory. The system has good compatibility and universalapplicability. It could be easily used in combination with other means of high-pressureobservation.