Study On Ferromagnetic Resonance Temperature Measurement Method Based On Magnetic Nanoparticles

Temperature is a crucial physical parameter reflecting the state of matter,so it is especially important to accurately measure the temperature in actual time.With the progress of science and technology,higher requirements are put forward for the acquisition of temperature information in many application fields,especially for the temperature measurement inside non-transparent materials.Compared with the traditional temperature measurement methods such as thermocouple,magnetic temperature measurement has the characteristics of noninvasive or minimally invasive and relatively large signal-to-noise ratio,so it has gradually become the current research hotspot.At present,the methods of obtaining temperature information by the magnetic resonance of hydrogen nucleus and magnetic nanoparticles are often seen in newspapers,but the methods of obtaining temperature information by the ferromagnetic resonance of electron spin are very rare.Therefore,the author tried to combine magnetic nanoparticles with ferromagnetic resonance and studied the temperature measurement method of magnetic nanoparticles under the condition of ferromagnetic resonance.Firstly,from the energy point of view of the spin system of magnetic nanoparticles,a ferromagnetic resonance frequency temperature-dependent model is established under the combined action of external static magnetic field and microwave excitation;The model gives the quantitative relationship between frequency,temperature,and magnetization.Secondly,due to the complexity of the measurement of magnetization,the relationship of magnetization,resonance frequency,and magnetic field can be deduced from the resonance conditions and the constitutive conditions of magnetic nanoparticles.It is substituted into the ferromagnetic resonance frequency temperature dependence model to obtain the sweep frequency temperature measurement model.Then,the frequency of microwave excitation is approximated to the resonance frequency.According to the further analysis of the resonance conditions,the relationship model between the applied static magnetic field and temperature based on the scanning field method is established.In this paper,the two models are verified by simulation experiments.The experimental results indicate that the two measurement models can measure the temperature,and have the feasibility and accuracy of temperature measurement.The paper also analyzes the anti-noise performance of the model and clarifies the applicable conditions of the model.Finally,aiming at the shortcomings of the model,the Langevin function is used to further improve the model,the relationship between electronic magnetic moment and atomic magnetic moment is analyzed,and the rationality of using the Langevin function to solve the magnetization is explained.In order to simplify the calculation,the Langevin function is linearly approximated,and an improved frequency temperature dependent model based on the linear approximation of the Langevin function is established.The simulation results of the model show that although the Langevin function is linearly approximated,the measurement precision is improved compared with the direct solution of the experiment.The method proposed in this paper can measure the internal temperature information of non-transparent materials under experimental conditions and has certain rationality.This work can provide ideas for future research on ferromagnetic resonance temperature measurement.