Effect of Amidogen Functionalization on Quantum Spin Hall Effect in Bi/Sb(111) Films

Abstract

Knowledge about chemical functionalization is of fundamental importance to design novel two-dimensional topological insulators. Despite theoretical predictions of quantum spin Hall effect (QSH) insulator via chemical functionalization, it is quite challenging to obtain a high-quality sample, in which the toxicity is also an important factor that cannot be ignored. Herein, using first-principles calculations, we predict an intrinsic QSH effect in amidogen-functionalized Bi/Sb(111) films (SbNH and BiNH), characterized by nontrivial Z invariant and helical edge states. The bulk gaps derived from p orbitals reaches up to 0.39 and 0.83 eV for SbNH and BiNH films, respectively. The topological properties are robust against strain engineering, electric field, and rotation angle of amidogen, accompanied with sizable bulk gaps. Besides, the topological phases are preserved with different arrangements of amidogen. The H-terminated SiC(111) is verified as a good candidate substrate for supporting the films without destroying their QSH effect. These results have substantial implications for theoretical and experimental studies of functionalized Bi/Sb films, which also provide a promising platform for realizing practical application in dissipationless transport devices at room temperature.

Dirac half-metallicity of Thin PdCl3 Nanosheets: Investigation of the Effects of External Fields, Surface Adsorption and Defect Engineering on the Electronic and Magnetic Properties

“…The search for a new member of the Dirac SGS family with the QAHE is of great importance for both fundamental interest and practical applications. Also, QSHE has been reported in previously studies 25,36 . The layered crystals of transition-metal trichloride, and the family of layered materials with the general formula TMX 3 (TM = Ti, V, Cr, Fe, Mo, Ru, Rh, Ir) and X is a halogen anion (X = Cl, Br, I) have become of interest for this purpose.…”

Strain Engineering and Electric Field Tunable Electronic Properties of Janus MoSSe/WX2 (X = S, Se) van der Waals Heterostructures

“…As applying strain is another effective approach to regulate the electronic structures of 2D materials; the band gap, Schottky barrier height, and topological states can be effectively tuned. Therefore, the in‐plane strain was applied to modulate the electronic properties of Janus MoSSe/WX 2 heterostructures. In‐plane biaxial strain, ϵ , on the heterostructures was applied by varying the cell parameter as a = ( ϵ + 1) × a 0 , where a 0 is the equilibrium lattice constant and a is strained lattice constant.…”

“…The maximum nontrivial band gap of 2D AsO can be enhanced from 89 to 130 meV under biaxial strain . Chemical functionalization is an effective approach to tailor the electronic and topological properties of 2D materials . The Janus structure can also be obtained by asymmetric functionalization of 2D materials.…”

Stable, one-dimensional suspended and supported monatomic chains of pnictogens: a metal–insulator framework

“…[74][75][76][77] Additionally, strain induced quantum spin Hall insulators 52 and giant and tunable Rashba spin splitting 53 from monolayers of SbBi binary compounds in buckled hexagonal structures have been predicted. Li et al showed that Bi(110) films 78 and amidogen modified Bi/Sb(111) films 79 are ideal platforms of the QSH effect for low-power dissipation devices. While interesting and fundamental effects were unveiled for 2D SbBi binary compounds, the chains of binary compounds of group-VA elements gained importance.…”