Electron Delocalization in Gate-Tunable Gapless Silicene

TL;DR

This paper investigates the electronic properties of gapless silicene under electric fields, showing that its delocalized state is stable against non-magnetic impurities due to suppressed backscattering, with implications for spin-polarized Dirac physics.

Contribution

It demonstrates that gapless silicene exhibits stable delocalized states with suppressed backscattering, supported by numerical and conductance scaling analyses.

Findings

No significant backscattering from non-magnetic impurities

Stable delocalized states in gapless silicene

Suppressed inter-valley scattering due to symmetry

Abstract

The application of a perpendicular electric field can drive silicene into a gapless state, characterized by two nearly fully spin-polarized Dirac cones owing to both relatively large spin-orbital interactions and inversion symmetry breaking. Here we argue that since inter-valley scattering from non-magnetic impurities is highly suppressed by time reversal symmetry, the physics should be effectively single-Dirac-cone like. Through numerical calculations, we demonstrate that there is no significant backscattering from a single impurity that is non-magnetic and unit-cell uniform, indicating a stable delocalized state. This conjecture is then further confirmed from a scaling of conductance for disordered systems using the same type of impurities.