腔自旋电子学是目前凝聚态物理中一个新兴的领域，它研究的是腔中磁体和量子化电磁场的相互作用。当腔中微波频率接近磁振子频率时，体系发生共振，磁振子和腔光子模式间产生杂化。这种杂化模式可以带来新的物理现象，通常把它形象地称为腔磁偏振子。磁振子和光子的耦合在磁学和量子光学领域间架起了一座桥梁，在光学与自旋电子学混合型装置上具有潜在应用。它们的耦合强度是评价量子操纵的标度。R. H. Dicke定律表明，光子和二能级体系的耦合强度g与二能级体系数目N的平方根成正比，g ∝√N。目前实验和理论考虑得较多的是自旋一致进动产生的铁磁共振模式。微米尺度的自旋驻波模式却很少得到人们的关注。根据R. H. Dicke定律，毫米尺度薄膜样品中的耦合强度就已经很弱。但是由于技术的发展，我们已经可以制造超低耗散的微波腔和钇铁石榴石样品，强耦合（耦合系数远大于自旋弛豫率和谐振器的耗散率）也是可以实现的。 本文中我们从理论上讨论了由自旋波驻波引起腔磁偏振子的问题。我们模拟真实实验微波腔的构造，将钇铁石榴石薄膜嵌入一维光学微腔，用散射矩阵表示体系每一部分的电磁场，从而计算出系统的透射系数，讨论不同磁性边界条件对腔磁偏振子的影响。我们理论和数值得到的结果表明，先前理论计算的透射光谱中没有铁磁共振模式是因为对磁矩面内和面外不合适的限制导致。通过调整面内对磁矩的限制，我们可以重现铁磁共振模式，得到和实验一样的结果。其次，反交叉关系变化特征背后的物理机制也被讨论，如在表面完全钉扎时耦合强度g(p)与薄膜厚度的平方根√d成正比，与模式数p成反比。 本文的创新点主要有： ? 我们考虑了不同磁性边界条件对腔磁偏振子的影响，为实验分析和解释提供了更多的细节； ? 我们解释了实验中观察到铁磁共振模式而先前数值模拟结果中却不存在的原因——表面磁矩完全钉扎； ? 我们的方法考虑了真实的实验装置，提供了大量的细节，容易重复和扩展来研究其他体系，如磁多层膜体系。

Cavity spintronics which studies the interaction between ferromagnet and a quantized electromagnetic field in cavity, is an emerging field in condensed matter physics. When the microwave frequency is close to the eigenfrequency of a magnon, the resonance will take place in the system. Magnon and cavity photon modes will hybridize. A piece of key physic——cavity magnon polariton (CMP) stand out. It bridges the gap between the fields of magnetism and quantum optics and possesses potential applications for quantum hybrid devices. Coupling strength between magnon and cavity photon measures the ability of quantum manipulations. A celebrated work which was accomplished by R. H. Dicke shows that the coupling strength g between photon and multiple two-level systems(TLS) is proportional to the square root of the number N of TLS , i.e. g ∝√N. Currently, ferromagnetic resonance (FMR) which is characterized by a uniform precession of the individual spins all across the ferromagnetic medium is under considerable consideration in recent experimental measurement and theoretical calculations. However, the standing spin wave (SSW)in μm-sized thin film receives little attention in the studies of CMP. According to Dicke’s law, the coupling strength in film sample becomes very small in the mm-sized samples. But, because of development of technology to produce ultra low damping rate of cavity and yttrium iron garnet(YIG), strong coupling (coupling parameter is more than the loss rates of the resonator and spin system, respectively) can be achieved as well. In this paper, we revisit the problem of CMP arising from SSW theoretically. Inserting YIG into one dimensional cavity, we express the electromagnetic field by transfer matrix method to simulate the structure of real experimental microwave cavity. Then we calculate the transmission and discuss the effect of various magnetization boundary condition on CMP. Moreover, we use our theory, in combination with numerical simulations, to show that the absence of FMR of microwave transmission spectrum in previous calculations is attributed to improper pinning condition at the surface. We recover the FMR by suitably lifting the is consistent with experimental results. In addition, we discussed physical mechanisms behind various features of anticrossing, e.g. the relation of coupling strength gp and thickness of film d is g(p) ∝√d/p, where p is mode number in the case of surface spins totally pinned . The innovation points in this paper are: ? We consider effect of additional magnetization boundary conditions on CMP in order to provide more insights into experimental analysis and explanation； ? We explain why both FMR and SSW can be observed simultaneously in spectra of experiment and not in previous numerical simulation. It amounts to surface spins totally pinned； ? Our method considers real experimental setup and provides a large amount of methodological details which can be followed and extend easily.