Possibility of realizing quantum spin Hall effect at room temperature instanene/Al2O3(0001)

Abstract

Two-dimensional quantum spin Hall (QSH) insulators with reasonably wide band gaps are imperative for the development of various innovative technologies. Through systematic density functional calculations and tight-binding simulations, we found that stanene on α-alumina surface may possess a sizeable topologically nontrivial band gap (~0.25 eV) at the Γ point. Furthermore, stanene is atomically bonded to but electronically decoupled from the substrate, providing high structural stability and isolated QSH states to a large extent. The underlying physical mechanism is rather general, and this finding may lead to the opening of a new vista for the exploration of QSH insulators for room temperature device applications.

The electronic properties of the stanene/MoS2 heterostructure under strain

“…2(a) shows the energy band structure of stanene. There is a Dirac cone at the K point and an optical gap at the G point, consistent with the results obtained by Wang et al 29 and Zhu et al 30 It is clear that stanene is a gapless semiconductor and it has a large carrier mobility due to the Dirac cone, which is benecial for potential applications in electric devices. However, for practical applications, a good substrate is necessary.…”

New Class of 3D Topological Insulator in Double Perovskite

“…Unlike semiconductors, the band gap of TI results from intrinsic spin-orbit coupling (SOC). For 2D materials, the band gap can be increased in a variety of ways, from incorporating heavy adatoms, 28 halogenation, 29 fluorination, 30 to choosing appropriate substrates 31,32 because of the open structure. As for 3D materials, on the other hand, there is little room for tuning the electronic structure and band gap; selecting heavier constituents and/or changing lattice structures seem to be the only feasible route.…”

Multiple odd-frequency superconducting states in buckled quantum spin Hall insulators with time-reversal symmetry

“…This model is not only theoretically tractable, but also experimentally realized in silicene, 31 the silicon analog of graphene with an experimentally achievable band gap in the bulk, as well as materials based on the heavier elements in group IV, such as germanene and stanene. [32][33][34][35][36] In superconducting QSHI systems we find, without the need of fine tuning, co-existing odd-ω spin-triplet (OT) and spin-singlet (OS) s-wave superconducting states. The OS pair amplitude is most universal and appears both in the bulk of the heavily doped QSHI and at the edge of finite-sized QSHI ribbons.…”