|Jun 04, 2020|
Modulation of topological edge states in twisted bismuthene homojunctions through moire superstructure(Nanowerk News) Scientists have successfully realized the modulation of topological edge states in twisted bismuthine homojunctions through Moiré superstructure, which has potential applications in nanoelectronics and quantum computing (Science Advances, "The effect of moiré superstructures on topological edge states in twisted bismuthene homojunctions").
|The topographic images (A,C,D) and schematic (B) of bismuthene/BP-Bi homostructure. (© IOP)|
|The two dimensional (2D) topological insulator (TI) is an insulating 2D material. It is a promising candidate for spin electronics and devices with minimal/negligible energy dissipation, which will be applicable in quantum computers and ultra-low energy electronic devices. However, the fabrication of robust TIs and the reliable tuning of their topological states are challenging.|
|In particular, 2D bismuthene (bismuth monolayer with a honeycomb atomic structure) is predicted as the best candidate for a 2D TI, but the preparation of free-standing modes in a single layer bismuthene has still not been realized, due to the strong influence of the substrate on the topological states.|
|Recently, Prof. CHEN Lan and Prof. WU Kehui from the Institute of Physics (IOP) of the Chinese Academy of Sciences, collaborating with Prof. Andrew Wee from the National University of Singapore, successfully synthesized a bismuthene homostructure using molecular beam epitaxy (MBE).|
|They found that a single layer of bismuthene can be grown on a single layer of black-phosphorus-like bismuth layer (BP-Bi) to form a vertical homostructure with different rotation angles between the two layers, which forms Moiré superstructure.|
|As the two layers in the homostructure have different atom arrangements, the interlayer interactions between these two layers are observed to be largely reduced and periodically modulated.|
|More importantly, they found that the topological edge states of bismuthene is also tunable as the periodically modulated interface interactions.|
|According to the scientists, moiré superstructure forms when a periodic lattice is overlaid on another similar lattice, typically at a small relative rotation angle. Using the moiré pattern formed by rotating two 2D materials relative to each other can potentially control performance of devices based on 2D materials.|
|The bismuthene homostructure realized in this work provides a novel paradigm that twisted stacking mode with the decoupled interlayer interactions can help to preserve the intrinsic topological property in a single layer bismuthene. It also proposes a new prototype to controllably tailor the topological edge states for quantum device applications.|
|Source: Chinese Academy of Sciences|
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