从量子力学层面上认识,到大学物理层面上理解顺磁性和抗磁性

UNDERSTANDING OF PARAMAGNETISM AND DIAMAGNETISM FROM THE VIEW OF QUANTUM MECHANICS TO THE UNIVERSITY PHYSICS

大学物理教科书中对物质磁性——顺磁性和抗磁性的机理描述不自洽.顺磁性用原子磁矩沿磁场方向的"倾倒"来解释,抗磁性用电子磁矩的"旋进"来解释.同样都是磁矩,为什么却有不同的行为呢?显然不能令人信服.本文将从量子力学角度给出两种磁性的来源,从中可以看出,顺磁和抗磁在量子力学的哈密顿量中正好是磁相互作用的展开项中的两项,这两项可以同时存在,也可以只有抗磁性,这取决于原子壳层的电子分布.在保持与量子力学一致的情况下,如何在大学物理层面上理解顺磁性和抗磁性?

In college physics textbooks, the descriptions about paramagnetism and diamagnetism are not self-consistent. Paramagnetism is explained by the rotation of atomic magnetic mo- ments towards the external field under the action of the applied magnetic field, but diamagnet ism is explained by the procession of electron＇s orbital magnetic moment. Why should magnetic moments in these two types of magnetic materials behave so differently？ The explanations in the textbooks are not very convincing. In this paper, paramagnetism and diamagnetism are interpreted by using quantum mechanics. The expansion for magnetic interaction in the Hamiltonian contains fwo terms that give rise to paramagnetism and diamagnetism, respectively. These two terms may coexist, and sometimes the one corresponding to paramagnetism disappears, depending on the electron configuration in the atomic structure. So, how do we come up with an explanation for these two types of magnetism at the level of university physics, and maintain the consistency with the interpretation of quantum mechanics？