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arXiv · 2404.00519

Electron Collimation in Twisted Bilayer Graphene via Gate-defined Moir\'e Barriers

Wei Ren·Xi Zhang·Ziyan Zhu·Moosa Khan·Kenji Watanabe·Takashi Taniguchi·Efthimios Kaxiras·Mitchell Luskin·Ke Wang
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Abstract

Electron collimation via a graphene pn-junction allows electrostatic control of ballistic electron trajectories akin to that of an optical circuit. Similar manipulation of novel correlated electronic phases in twisted-bilayer graphene (tBLG) can provide additional probes to the underlying physics and device components towards advanced quantum electronics. In this work, we demonstrate collimation of the electron flow via gate-defined moir\'e barriers in a tBLG device, utilizing the band-insulator gap of the moir\'e superlattice. A single junction can be tuned to host a chosen combination of conventional pseudo barrier and moir\'e tunnel barriers, from which we demonstrate improved collimation efficiency. By measuring transport through two consecutive moir\'e collimators separated by 1 um, we demonstrate evidence of electron collimation in tBLG in the presence of realistic twist-angle inhomogeneity.

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Wei Ren, Xi Zhang, Ziyan Zhu, Moosa Khan, Kenji Watanabe, Takashi Taniguchi, Efthimios Kaxiras, Mitchell Luskin, Ke Wang. 2024-03-31. Electron Collimation in Twisted Bilayer Graphene via Gate-defined Moir\'e Barriers. https://arxiv.org/abs/2404.00519

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