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arXiv · 2411.10901

Twisted Type-II Rashba Homobilayer: A Platform for Tunable Topological Flat Bands

Xilong Xu·Haonan Wang·Li Yang
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Abstract

The recent discovery of topological flat bands in twisted transition metal dichalcogenide homobilayers and multilayer graphene has sparked significant research interest. We propose a new platform for realizing tunable topological moire flat bands: twisted type-II Rashba homobilayers. The interplay between Rashba spin-orbit coupling and interlayer interactions generates an effective pseudo-antiferromagnetic field, opening a gap within the Dirac cone with non-zero Berry curvature. Using twisted BiTeI bilayers as an example, we predict the emergence of flat topological bands with a remarkably narrow bandwidth (below 20 meV). Notably, the system undergoes a transition from a valley Hall insulator to a quantum spin Hall insulator as the twisting angle increases. This transition arises from a competition between the twisting-driven effective spin-orbit coupling and sublattice onsite energies presented in type-II Rashba moir\'e structures. The high tunability of Rashba materials in terms of the spin-orbit coupling strength, interlayer interaction, and twisting angle expands the range of materials suitable for realizing and manipulating correlated topological properties.

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Xilong Xu, Haonan Wang, Li Yang. 2024-11-16. Twisted Type-II Rashba Homobilayer: A Platform for Tunable Topological Flat Bands. https://doi.org/10.1002/adfm.202425454

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