Phys. Rev. B, 107, 224426 (2023)
Surface Chiral Berry Plasmons on Disordered Permalloys
Zhen Liang1 and Tianyu Liu1,2,*
1 Department of Physics and Center for Joint Quantum Studies, School of Science, Tianjin University, Tianjin 300350, China
2 Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Tianjin 300350, China
* tianyu_liu@tju.edu.cn
Abstract
We investigate the surface plasmons propagating on disordered bulk permalloys (Pys), whose magnetization breaks the time reversal symmetry, causing the surface plasmons to possess chirality in the absence of magnetic fields under the interplay of the anomalous Hall conductivity (AHC) and the boundary conditions at the surface. Based on the collisionless hydrodynamic model, we incorporate the effect of interband transitions into the dispersion of surface plasmons. As we show, the AHC will split the forward and backward propagating surface plasmons into two modes, while the p-d transitions in bulk Py will work against the AHC, yielding slower propagation surface chiral Berry plasmons (CBPs), and even ceasing the presence of surface modes. The resulting surface CBP has a broad bandwidth ranging from visible light to infrared frequency. The free-field chirality may provide a new knob to control the chiral transport of light, as well as a new probe for detecting the intrinsic AHC in ferromagnetic metals.
