2D O-PTl monolayer: a robust large bandgap topological insulator

Abstract

Searching for ideal two-dimensional (2D) topological insulators (TIs) with large bandgaps is significant for the realization of the quantum spin Hall effect (QSHE) at room temperature. By employing ab initio calculations based on the density functional theory, we predict a novel 2D TI, semi-oxidized phosphorus thallium O-PTl, which harbors a series of excellent properties, such as high flexibility, chemical stability, and a large tunable 2D TI bandgap. In contrast to the monolayer PTl, semi-oxidation on one side of P induces a large TI bandgap of 403 meV, which can be further enlarged to 460 meV by biaxial strain, far exceeding the temperature required for practical application. Due to the semi-oxidation on one side of P, the material is chemically stable against surface oxidization when grown on suitable substrates forming heterostructures. For the O-PTl/BN and O-PTl/graphane heterostructures, we find that the nontrivial topological bandgap of O-PTl is almost not affected by substrate, which is crucial to the experimental realization of QSHE. Our results demonstrate a new type of 2D TI materials and provide a new alternative strategy to devise topological electronic devices operating at room temperature.

Bandgap mechanisms and wave characteristics analysis of a three-dimensional elastic metastructure

“…The existing research work on EMs (Lee and Iizuka, 2019; Wang and Wang, 2018; Yz et al. , 2022; Guo et al ., 2020; Kumar and Pal, 2020; Xue et al ., 2020) mainly focused on one-dimensional and two-dimensional structures, and rarely involve three-dimensional EM. Sigalas et al.…”

“…The existing research work on EMs (Lee and Iizuka, 2019;Wang and Wang, 2018;Yz et al, 2022;Guo et al, 2020;Kumar and Pal, 2020;Xue et al, 2020) mainly focused on onedimensional and two-dimensional structures, and rarely involve three-dimensional EM. Sigalas et al (Sigalas and Soukoulis, 1995) first proved theoretically the existence of elastic wave bandgap in three-dimensional periodic lattice materials.…”

Coexistence of giant Rashba spin splitting and quantum spin Hall effect in H–Pb–F

“…[8] In recent years, a large number of materials with RSS phenomenon have been found experimentally and theoretically. Such as MoS 2 /Bi 2 Te 3 heterojunction (0.27 eV• Å-2.5 eV• Å), [9] semihydrogenated graphene and topological insulator heterojunction (0 eV• Å-0.783 eV• Å), [10] MoS 2 /Bi (1.097 eV• Å), [11] Janus bilayer transition metal dichalcogenides (0 eV• Å-0.38 eV• Å), O-PTl (1.736 eV• Å), [12] and Pb coverd Bi 2 Se 3 (1.98 eV• Å) [13] are predicted theoretically. However, these theoretically predicted structures are difficult to realize experimentally.…”