Rare Earth Fluoride The Ndf <sub> 3 </ Sub> Magnetic Properties Of Factors

The thesis reports the magnetic properties of paramagnetic light rare earth trifluoride NdF₃ under low temperature and the high magnetic field by using quantum theory. The theoretical quantitatively results are compared with the experimental ones, in order to probe into the theory of the microscopic mechanism of magnetization of substance when the temperature is low and applied magnetic field is high.Magnetism is one of the basic attributes of the substance. The theoretical investigation of magnetic material is beneficial to further research and exploit the new magnetic product in the experiment. As we know, temperature and applied magnetic field (H) has strong influence on the magnetic properties (M). So in the recent years, high magnetic field has been the focus on experiment. In 1999, M.Guillot, a French physical scientist, reported the magnetic properties in single crystal NdF₃, which showed some specific properties. Within their experimental conditions, M was observed to be linear versus H above 40K.Below 40K,a more and more pronounced curvature of the M (H) curves is found as is shown in the thesis. It should be noted that at 1.6K,the saturation is attained in relatively low applied field (50KOe). In 1998, M.Guillot reported the magnetic properties of erbium gallium gallate (ErGaG) under the high magnetic, and which has the same specialties magnetic behave. All the experiment phenomena aroused the research interest of many theoretical scientists. In the literature, the magnetic susceptibility studies when considered the low temperature and strong applied magnet field performed large deviations from the experiment ones by usingcurrent theory.After modified the current traditional model, this paper shows the investigation on the magnetic properties of the single crystal NdF₃ at low temperature 1.6K, 4.2K, 40K and under magnetic field 0³00KOe by quantum theory, and gains the magnetizationwhich is in good agreement with the result of the experiment. The modifying of the model base on two aspects, one is considering of the shield of rare earth and modifies the crystal field parameter which calculated by using the point-charge model, the other considering the function of super-exchange of rare earth ions and modify the HamiltonianUsing quantum theory, taking the special microscopic structure of NdF3 into account, we calculate and analyze the splitting of the rare iron 4/"■' configurationmultiple 4115/2 -. 4Il3/2 ^ 4I,1/2 and 419/2 .Through quantitative calculation we find thespin orbit interaction has different effect in different materials through compare with the ErGaG Material. The change of the temperature has a main effect on the electron occupied probability to all the energy levels and has effect on the magnetization further. We find that crystal field shield factor, super-exchange interactions are also crucial factors in determining the magnetization. The result calculated by using the modified model explain the experimental ones especially when the temperature is low and magnet field is high. That also play a constructive role in understanding the influential factor of paramagnetic magnetization in NdF3 when applied temperature is low and magnet field is high.