Thermal Spin Transport Properties of F/Cl Edge-Modified Zigzag Graphene Nanoribbons

We report herein the calculated thermal spin-transport properties of edge-modified zigzag graphene nanoribbons (ZGNRs) based on chemical modification of one edge with OH groups and of the other edge with F or Cl atoms. For these calculations, we use a nonequilibrium Green’s function combined with density-functional theory. By applying a temperature field, we find that edge modification of ZGNRs with F atoms leads to single-spin negative differential resistance and a spin-filter effect (SFE). Edge modification of ZGNRs with Cl atoms leads to a weak spin-Seebeck effect and a SFE, respectively, and the two devices exhibit the spin-switcher effect. In addition, we calculate the band structures of these devices and find that both have metallic properties. We examine the thermopower and figure of merit of the two devices and confirm that these interesting effects appear in both devices. These interesting effects have also been observed in other spin nanodevices.