Topological spin-valley filtering effects based on hybrid silicene-like nanoribbons

Abstract

Topological edge states have crucial applications in nano spintronics and valleytronics devices, while topological inner-edge states have seldom been extensively researched in this field. Based on the inner-edge states of the hybridized zigzag silicene-like nanoribbons, we investigate their transport properties. We propose two types of spin-valley filters. The first type can generate two different spin-valley polarized currents in output leads, respectively. The second type outputs the specific spin-valley polarized current in only one of the output leads. All these inner-edge states have the spin-valley-momentum locking property. These types of filters can switch the output spin-valley polarizations by modulating the external fields. Besides, we also find that the device size plays a crucial role in designing these spin-valley filters. Moreover, the local current distributions are calculated to visualize the detailed transport process and understand the mechanism. The mechanism lies that the spin-valley polarized current can nearly freely pass through the system with the same momentum, spin and valley degrees of freedom. The small reflection of the current results from the inter-valley scattering. In particular, we also consider the realistic (disorder) effects on the performance of these filters to ensure the robustness of our systems. We believe these spin-valley current filtering effects have potential applications in the future spintronics and valleytronics device designs.