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arXiv · 1905.04515

Large-area, periodic, and tunable intrinsic pseudo-magnetic fields in low-angle twisted bilayer graphene

Haohao Shi·Zhen Zhan·Zhikai Qi·Kaixiang Huang·Edo van Veen·Jose Angel Silva-Guillén·Runxiao Zhang·Pengju Li·Kun Xie·Hengxing Ji·Mikhail I. Katsnelson·Shengjun Yuan·Shengyong Qin·Zhenyu Zhang
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Abstract

A properly strained graphene monolayer or bilayer is expected to harbour periodic pseudo-magnetic fields with high symmetry, yet to date, a convincing demonstration of such pseudo-magnetic fields has been lacking, especially for bilayer graphene. Here, we report the first definitive experimental proof for the existence of large-area, periodic pseudo-magnetic fields, as manifested by vortex lattices in commensurability with the moir\'e patterns of low-angle twisted bilayer graphene. The pseudo-magnetic fields are strong enough to confine the massive Dirac electrons into circularly localized pseudo-Landau levels, as observed by scanning tunneling microscopy/spectroscopy, and also corroborated by tight-binding calculations. We further demonstrate that the geometry, amplitude, and periodicity of the pseudo-magnetic field can be fine-tuned by both the rotation angle and heterostrain applied to the system. Collectively, the present study substantially enriches twisted bilayer graphene as a powerful enabling platform for exploration of new and exotic physical phenomena, including quantum valley Hall effects and quantum anomalous Hall effects.

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Haohao Shi, Zhen Zhan, Zhikai Qi, Kaixiang Huang, Edo van Veen, Jose Angel Silva-Guillén, Runxiao Zhang, Pengju Li, Kun Xie, Hengxing Ji, Mikhail I. Katsnelson, Shengjun Yuan, Shengyong Qin, Zhenyu Zhang. 2019-05-11. Large-area, periodic, and tunable intrinsic pseudo-magnetic fields in low-angle twisted bilayer graphene. https://doi.org/10.1038/s41467-019-14207-w

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