Abstract
The quantum spin Hall insulators predicted ten years ago and now experimentally observed are instrumental for a break- through in nanoelectronics due to non-dissipative spin-polarized electron transport through their edges. For this transport to persist at normal conditions, the insulators should possess a sufficiently large band gap in a stable topological phase. Here, we theoretically show that quantum spin Hall insulators can be realized in ultra-thin films constructed from a trivial band insulator with strong spin-orbit coupling. The thinnest film with an inverted gap large enough for practical applications is a centrosymmetric sextuple layer built out of two inversely stacked non-centrosymmetric BiTeI trilayers. This nontrivial sextuple layer turns out to be the structure element of an artificially designed strong three-dimensional topological insulator Bi2Te2I2. We reveal general principles of how a topological insulator can be composed from the structure elements of the BiTeX family (X = I, Br, Cl), which opens new perspectives towards engineering of topological phases.
Highlights
Propositions of different 2D topological insulators (TIs) with honeycomb- or square-lattice structures and a large inverted gap enabling room-temperature operating[17]
Ab initio approaches to electronic structure, especially those based on the density functional theory (DFT), have become a powerful tool to search for new materials with unique properties
It was suggested that 2D TIs can be produced from a thin film of layered 3D TIs of the Bi2Se3 family, where the hybridization between the opposite surfaces of the film opens a gap at the Dirac point (DP)
Summary
Propositions of different 2D TIs with honeycomb- or square-lattice structures and a large inverted gap enabling room-temperature operating[17]. To describe the low-energy properties of Bi2Te2I2 and its films, we derive four-band k·p Hamiltonians from the ab initio wave functions.
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