Spin-resolved photomodulated electronic properties of ferromagnetic kagome lattices

Abstract

We study theoretically the band structures and angle-resolved photoemission spectroscopy of both monolayer and bilayer kagome lattices irradiated by variously polarized monochromatic light based on the Floquet-Bloch theory. The polarization of light plays distinctive roles in the different energy regimes of kagome bands. The linearly polarized light predominantly affects the flat bands at the bottom of the kagome band, while the circularly polarized light engenders spin-resolved massive Dirac cones whose spin species can be switched by the polarization direction. The edge states of kagome ribbons exhibit a spatially anisotropic quantum spin Hall effect conforming to the nontrivial topology of kagome bands. In kagome bilayers, we take into account the electric field component of monochromatic light which results in a band gap in flat bands in the case of oblique incidence. This shows that the polarized light provides us a versatile tool to manipulate not only the two-dimensional and quasi-one-dimensional band structures, but also the anomalous Hall conductivity by either the polarization or the incident plane of monochromatic light.