Antiferromagnetic Spin-Ordered Topology of Surface Functionalized Sb and Bi Monolayer Nanoflakes

Abstract

Scale effect and topological frustration have been found to induce magnetic ordering in graphene-like nanoflakes. Based on triangular nanoflakes, the chemically surface-modified Sb and Bi monolayer nanotopological structures are proposed as spintronic logic gates, and their first-principles spin-polarized electron-structure calculations are performed to provide a theoretical basis for developing a new generation of ultrafast spin devices. The net spin of surface-functionalized Sb and Bi monolayer triangular nanoflakes mainly originates from the topological edge-states, exhibiting a sufficiently large spin bandgap, thus enabling stable large spin magnetic moments even under conditions of internal or edge defects and room-temperature electron excitation. The double-triangular nanoflakes of surface-functionalized Sb and Bi monolayers exhibit two stable spin configurations: ferromagnetic coupling and antiferromagnetic coupling. These configurations can serve as elementary variables for spin logic gates. Even at a linear scale as small as 2 nm, the spin coupling energy remains greater than 120 meV, and the error rate decreases below 1×10-5 at room temperature, demonstrating the spin logic gates of triple triangular nanoflakes protected by scattering-prohibited topology.