Searching for large-gap quantum spin hall insulators: boron-nitride/(Pb, Sn)/α-Al₂O₃sandwich structures

Abstract

Topological insulators hold great potential for efficient information processing and storage. Using density functional theory calculations, we predict that a honeycomb lead monolayer can be stabilized on an AlO (0001) substrate to become topologically non-trivial with a sizeable band gap (∼0.27 eV). Furthermore, we propose to use a hexagonal boron-nitride (h-BN) monolayer as a protection for the topological states of Pb/AlO and Sn/AlO. Our findings suggest new possibilities for designing and protecting two-dimensional TIs for practical applications.

Engineering topological states in a two-dimensional honeycomb lattice

“…To date, exploration of high-temperature (namely, large-gap) QSH and QAH effects has been a key issue for practical application. Although extensive efforts have been made, 11–39 the observation temperatures of these two effects are still very low. Especially for the QAH effect, its observation temperature is only ∼1 K. 40 Generally, 2DTIs that consist of heavy metals with strong SOC are highly desired as these materials may host large nontrivial band gaps.…”

Formation of a monolayer h-BN nanomesh on Rh (111) studied using in-situ STM

“…Moreover, while consisting into a stacked heterostructure with other 2D materials, h-BN can further engineer the physical properties of the supporting layers, e.g., the h-BN substrate can induce a finite band gap in the supported graphene [17,18], and the light-matter interaction is enhanced in the graphene/h-BN van der Waals heterostructures [19]. Due to these advantages, h-BN is becoming one of most important candidates as ideal substrate, dielectric gating layer and insulating interlayer in the concepts of ultra-thin devices based on 2D materials, thus at-tracts more and more research interest [20][21][22][23].…”

Selective Substrate-Orbital-Filtering Effect to Realize the Large-Gap Quantum Spin Hall Effect

“…The first experimentally confirmed QSH insulator is the HgTe quantum well, , which has a very small gap. Since then, many 2D QSH insulators, − some with a large gap, have been theoretically predicted and a few experimentally confirmed, including, e.g., HgTe/CdTe QWs, InAs/GaSb QWs, Bi bilayer, and 1T′ WTe 2 monolayer. − …”