Influence of edge magnetization and electric fields on zigzag silicene, germanene and stanene nanoribbons

TL;DR

This study investigates how edge magnetization and electric fields influence the electronic and magnetic properties of zigzag silicene, germanene, and stanene nanoribbons, revealing complex edge states and potential spintronics applications.

Contribution

The paper introduces a multi-orbital tight-binding model and an effective low-energy model to describe edge states, highlighting non-linear dispersions and tunable spin polarizations in these nanoribbons.

Findings

Edge states exhibit non-linear energy dispersions due to multi-orbital effects.

Edge magnetization can be induced and tuned by electric fields.

Band anti-crossing occurs with opposite spins in germanene and stanene nanoribbons.

Abstract

Using a multi-orbital tight-binding model, we have studied the edge states of zigzag silicene, germanene, and stanene nanoribbons (ZSiNRs, ZGeNRs and ZSnNRs, respectively) in the presence of the Coulomb interaction and a vertical electric field. The resulting edge states have non-linear energy dispersions due to multi-orbital effects, and the nanoribbons show induced magnetization at the edges. Owing to this non-linear dispersion, ZSiNRs, ZGeNRs and ZSnNRs may not provide superior performance in field effect transistors, as has been proposed from single-orbital tight-binding model calculations. We propose an effective low-energy model that describes the edge states of ZSiNRs, ZGeNRs, and ZSnNRs. We demonstrate that the edge states of ZGeNR and ZSnNR show anti-crossing of bands with opposite spins, even if only out-of-plane edge magnetization is present. The ability to tune the spin polarizations of the edge states by applying an electric field points to future opportunities to fabricate silicene, germanene and stanene nanoribbons as spintronics devices.