Systematic study on stanene bulk states and the edge states of its zigzag nanoribbon

Abstract

Stanene, as a counterpart of graphene, but with much larger spin-orbit coupling (SOC) strength, has recently been synthesized experimentally. Based on first principle calculations and an effective model, we systematically study the electronic and topological properties of bulk stanene under vertical electric field and biaxial strain, which can be naturally introduced by substrates. We find that a topological nontrivial-trivial transition occurs under a critical vertical electric field and an insulator-metal transition happens under critical biaxial strains. We also systematically study the edge state of zigzag nanoribbons. We find that the topological edge state has strong nonlinear dispersion that is different from the previous oversimplified tight-binding (TB) model. A much more practical TB model is built, which captures the strongly nonlinear dispersion of the edge states very well. We investigate four magnetic configurations of the zigzag ribbon edge states in detail and find that the emergence of magnetism for the edge atoms and the magnetization direction have a remarkable impact on the spincurrent-carrying edge channels. Furthermore, a half-metallic state can be induced in stanene nanoribbons by applying a transverse electric field, and opposite spin channels can be chosen by reversing the electric field direction. Our results are instructive for future research and applications on stanene and other related buckled systems.

Emerging Applications of Elemental 2D Materials

“…This phenomenon supports the coexistence of the charge and pure spin current, which may have great potential for electrically controllable spintronic devices . For stanene NRs, Fu et al obtained four types of edge magnetic configurations out‐of‐plane ferromagnetic (OP‐FM), out‐of‐plane anti‐ferromagnetic (OP‐AFM), in‐plane ferromagnetic (IP‐FM), and in‐plane antiferromagnetic (IP‐AFM) . All four magnetic states were predicted to be ≈7–8 meV per edge atom lower energy than the nonmagnetic states, suggesting spontaneous magnetism.…”

“…All four magnetic states were predicted to be ≈7–8 meV per edge atom lower energy than the nonmagnetic states, suggesting spontaneous magnetism. On applying transverse electric field, half‐metallic states could be induced in nanoribbons, which has promising prospects in magnetic control and spintronics . In a recent study, interaction of various gases with stanene was investigated by Garg et al where the author found that stanene gas systems show Rashba type spin‐splitting, which is very promising for spintronics applications …”

“…Broek et al suggested that applying lateral strain on stanene under out‐of‐plane electric field can open up the bandgap up to 0.21 eV, while Modarresi and co‐workers suggested that the SOC bandgap of ≈0.07 eV in stanene closes under applied strain . Fu et al studied stanene and predicted a metal–insulator transition under critical biaxial strain . For penta‐graphene NRs, the bandgap was shown to decrease with tensile and bending strain .…”

“…For monolayer silicene, a bandgap varies linearly with electric field strength and a total gap as high as 18 meV was predicted, which could be increased to 0.25 eV at electric field strengths of 1 V Å −1 when sandwiched between h ‐BN layers . Fu et al studied the electronic and topological properties of stanene and predicted a topological nontrivial–trivial transition under a critical vertical electric field …”

“…Rajbanshi et al studied penta‐graphene nanoribbons and also suggested that the bandgap increases with reducing nanoribbon width . On the contrary, Fu et al predicted that for stanene NRs, edge states have a dispersion width of ≈83 meV, regardless of ribbon width . Yu et al suggested that bandgap in penta‐graphene could be modulated by up to a factor of 2–3 by manipulating number of layers, stacking arrangement as well as their misalignment…”