摘要
Non-Abelian gauge potentials are quite relevant in subatomic physics, but they are relatively rare in a condensed matter context. Here we report the experimental evidence for non-Abelian gauge potentials in twisted graphene bilayers by scanning tunneling microscopy and spectroscopy. At a magic twisted angle, θ≈(1.11±0.05)°, a pronounced sharp peak, which arises from the nondispersive flat bands at the charge neutrality point, is observed in the tunneling density of states due to the action of the non-Abelian gauge fields. Moreover, we observe confined electronic states in the twisted bilayer, as manifested by regularly spaced tunneling peaks with energy spacing δE≈vF/D≈70meV (here vF is the Fermi velocity of graphene and D is the period of the moiré patterns). This indicates that the non-Abelian gauge potentials in twisted graphene bilayers confine low-energy electrons into a triangular array of quantum dots following the modulation of the moiré patterns. Our results also directly demonstrate that the Fermi velocity in twisted bilayers can be tuned from about 106m/s to zero by simply reducing the twisted angle of about 2°.
源语言 | 英语 |
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文章编号 | 081406 |
期刊 | Physical Review B - Condensed Matter and Materials Physics |
卷 | 92 |
期 | 8 |
DOI | |
出版状态 | 已出版 - 19 8月 2015 |
已对外发布 | 是 |