Stability and electronic properties of bilayer graphene spirals

Spiral topology offers many potential applications to next-generation nanoelectronic devices. The ab-initio simulations are used to investigate the stability and electronic properties of the hexagonal and triangular double-layer spiral (DLS). A room temperature molecular dynamics (MD) simulation reveals that the AA stacking of triangular DLS (t-DLS) is thermodynamically stable, however, the AA stacking of hexagonal DLS (h-DLS)is found to get distorted. When h-DLS and t-DLS are subjected to tensile strain the h-DLS behaved elastically, however, the t-DLS is extremely brittle. Both h-DLS and t-DLS are observed to be metallic in an equilibrium state. On applying an electric field, the h-DLS remains metallic, whereas, the t-DLS becomes a semiconductor. The bandgap of t-DLS is observed to open up even for a small magnitude of electric field. Furthermore, we also found that the triangular-shaped bilayer spiral topology gives rise to an intrinsic Rashba splitting. Our study opens up new and innovative ideas for investigating the spiral-shaped nano-structures.