Optically and electrically controlled switchers and electron beam splitters based on topological edge states

Abstract

Recently, topological edge states have attracted rapid attention for designing low-power consumption electronics due to their topological protection and suppression of backscattering. We study the transport properties of inner and outer edge states in a three-terminal device composed of hybrid zigzag graphene nanoribbons based on our derived formulas of local bond current and transmission coefficient with the wave-function matching technique. Particularly, by electrically modulating inner edge state in the conductor region, the valley current can be flipped as the charge current that is switched into one lead or split into two transmitted leads, leading to the charge switchers and electron beam splitters when the incident lead and transmitted leads are set as antichiral inner edge state and chiral edge states, respectively. Furthermore, when three leads are both modulated as antichiral inner edge state by the spatially varying off-resonant circularly polarized (ORCP) light, the charge switchers and electron beam splitters are accordingly converted into the valley switchers and electron beam splitters. The behavior of the switchers and splitters originates from the cooperative effects of the lager wave-vector mismatch between different valleys, and the distributions of lateral and vertical inner edge states. Moreover, the proposed devices could be cut off by the staggered electric field due to the gap effect, and are robust against the edge magnetism and the spin-orbit coupling. These findings are expected to apply for optically and electrically controlled topological devices.

Keywords

• Topological edge states
• Zigzag graphene nanoribbon
• Local bond current
• Splitter and switcher