Surface plasmon-phonon-magnon polariton in a topological insulator-antiferromagnetic bilayer structure
Surface plasmon-phonon-magnon polariton in a topological insulator-antiferromagnetic bilayer structure
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DOI：
10.1103/physrevmaterials.6.085201
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发表时间：
2022-05
影响因子：
3.4
通讯作者：
D. To;Zhengtianye Wang;Yongchen Liu;Wei-Peng Wu;M. Jungfleisch;J. Xiao;J. Zide;S. Law;M. Doty
中科院分区：
文献类型：
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作者：
D. To;Zhengtianye Wang;Yongchen Liu;Wei-Peng Wu;M. Jungfleisch;J. Xiao;J. Zide;S. Law;M. Doty
我们提出了一种计算研究杂化材料表面极化模式的稳健技术。我们使用半经典模型，使我们能够理解混合系统集体激发之间相互作用背后的物理学，并开发了散射和转移矩阵方法，该方法施加适当的边界条件来求解麦克斯韦方程组，并推导出描述由N个组成材料组成的异质结构中表面极化子的一般方程。我们将该方法应用于由拓扑绝缘体（TI）和反铁磁材料（AFM）组成的测试结构中，研究得到的表面狄拉克等离子体-声子-磁振子极化子（DPPMP）。我们发现两种组分的激发之间的相互作用导致了杂化模式的形成和DPPMP色散关系中避免交叉点的出现。对于bi2se3ti材料的特殊情况，随着TI薄膜厚度的增加，低于2thz的低频极化子分支红移，这导致TI层厚度的上限，这将允许观察到强耦合和杂化态的出现。我们还发现，TI和AFM之间的耦合强度取决于磁偶极子的大小和AFM材料中磁振子的线宽，以及TI中狄拉克等离子体的费米能量，这一耦合强度由两个极化子分支在磁振子共振频率处的避免交叉分裂的幅度来参数化。最后，我们预测具有极高质量的材料，即低散射损失率，对于实现实验可观察到的TI和AFM之间的强耦合至关重要。
We present a robust technique for computationally studying surface polariton modes in hybrid materials. We use a semi-classical model that allows us to understand the physics behind the interactions between collective excitations of the hybrid system and develop a scattering and transfer matrix method that imposes the proper boundary conditions to solve Maxwell’s equations and derive a general equation describing the surface polariton in a heterostructure consisting of N constituent materials. We apply this method to a test structure composed of a topological insulator (TI) and an antiferromagnetic material (AFM) to study the resulting surface Dirac plasmon-phonon-magnon polariton (DPPMP). We find that interactions between the excitations of the two constituents result in the formation of hybridized modes and the emergence of avoided-crossing points in the dispersion relations for the DPPMP. For the specific case of a Bi 2 Se 3 TI material, the polariton branch with low frequency below 2 THz redshifts upon increasing the thickness of TI thin film, which leads to an upper bound on the thickness of the TI layer that will allow an observable signature of strong coupling and the emergence of hybridized states. We also find that the strength of the coupling between the TI and the AFM, which is parameterized by the amplitude of the avoided-crossing splitting between the two polariton branches at the magnon resonance frequency, depends on the magnitude of the magnetic dipole and the line width of the magnon in the AFM material as well as on the Fermi energy of Dirac plasmon in the TI. Finally, we predict that materials with extremely high quality, i.e. low scattering loss rate, are essential to achieve an experimentally-observable strong coupling between a TI and AFM.