Edge-modulated dual spin-filter effect in zigzag-shaped buckling Ag2S nanoribbons

Abstract

Unlike MoS₂, single-layered Ag₂S nanoribbons (Ag₂SNRs) exhibit a nonmetal-shrouded and a zigzag-shaped buckling structure and possess two distinct edges, S- or Ag-terminated ones. By performing first principle calculations, the spin-dependent electron transport of Ag₂SNRs in a ferromagnetic state has been investigated. It is found that the SS- and AgAg-terminated Ag₂SNRs exhibit semi-metallic characteristics, but with opposite spin-polarized directions. And AgS-terminated ones show metallic characteristics, but with completely spin-unpolarized transmission. That is to say, all three states, i.e., spin up polarized, spin down polarized and spin unpolarized ones, could be achieved by modulating the edge geometry. Further analysis shows that, the spatial separation on edges of the energy states with different spins around E_F is responsible for the switch in the three states. The system could operate as a dual spin-filter, and the direction of the spin polarization can be switched by the edge morphology. Furthermore, calculations show that such a phenomenon is robust to the width of the ribbon and strain, showing great application potential.