Twist-Induced Dimensional Crossover and Topological Phase Transitions in Bismuthene Quasicrystals

Twisted bismuthene homojunctions, comprised of a Bi(111) bilayer atop two Bi(110) monolayers, exhibit a distinct growth orientation that is facilitated by self-assembly. Our cross-sectional structural analysis reveals an unexpected growth alignment of Bi(110) layers on transition-metal dichalcogenides, deviating from the anticipated Bi(111) bilayer structure. This self-assembly process, driven by the crystal symmetry interplay, induces a topological phase transition beyond a critical thickness. The dimensional crossover in the Fermi surfaces marks the electronic transition from two-dimensional (2D) Bi(110) to 1D Bi(111) quasicrystals. Additionally, the emergence of the topologically nontrivial band structures, an enhanced 1D carrier density, and a metal–insulator transition through band inversion indicate that the twisted bismuthene quasicrystals are promising candidates for higher-order topological quasicrystalline insulators. These findings pave the way for low-resistance contacts in 2D transistors, advancing the development of next-generation electronic devices.