Experimental Study Of Isothermal Remanent Magnetization Detection System Based On Rubidium Atomic Ensemble

With the development and wide application of environmental magnetism,isothermal remanent magnetization（IRM）of materials has become one of the important research methods in the study of many environmental problems such as rock-forming processes,paleoclimate evolution,soil deposition,identification of pollutant sources,and environmental climate change.The usual magnetometers used for IRM detection are fluxgate magnetometer and superconducting quantum interference magnetometer.Among them,fluxgate magnetometers are highly portable,while superconducting quantum interference magnetometers have high accuracy of magnetic field measurement.However,in practical applications,the detection of IRM properties of substances requires instruments with good portability and high measurement accuracy at the same time.The above two instruments are unable to meet the demand for practical application,so it is necessary to study the IRM measurement system with both precision magnetic field measurement and easy portability.Benefit from the rapid development of atomic measurement technology in recent years,atomic magnetometers have the advantages of high sensitivity and miniaturization of the device at present.Thus,this paper uses an atomic magnetometer with sensitivity of 0.85 p T/（Hz）^1/2at 1 Hz magnetic field as the sensor for IRM measurement system.After that,an IRM detection system was constructed by combining the atomic magnetometer with a magnetization device.The sensitivity of the IRM detection system is reduced compared to that of the atomic magnetometer system because the magnetization device is directly above the atomic cell and generates a large gradient magnetic field in the space of the atomic cell.Currently,the sensitivity of this system can reach 6 p T/（Hz）^1/2 at 1 Hz magnetic field in a large gradient environmental magnetic field.Next,the reasons affecting the sensitivity of the IRM detection system and the main sources of noise in the device were analyzed.And then,the surface soil near the Cherry River in Minhang campus of East China Normal University and the snow-covered soil along a main road in Hegang,Heilongjiang Province were collected as the test samples.After IRM detection,the IRM curves of the two samples were plotted.From the IRM curves,it was found that the amount and type of magnetic materials contained in the two samples were different.The study shows that the system with high sensitivity and potential for miniaturization has important development prospects in the fields of environmental magnetism and geological exploration.