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arXiv · 1811.02282

Magnetism near half-filling of a van Hove singularity in twisted graphene bilayer

Yi-Wen Liu·Jia-Bin Qiao·Chao Yan·Yu Zhang·Si-Yu Li·Lin He
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Abstract

Twisted graphene bilayers (TGBs) have low-energy van Hove singularities (VHSs) that are strongly localized around AA-stacked regions of the moire pattern. Therefore, they exhibit novel many-body electronic states, such as Mott-like insulator and unconventional superconductivity. Unfortunately, these strongly correlated states were only observed in magic angle TGBs with the twist angle theta~1.1°, requiring a precisely tuned structure. Is it possible to realize exotic quantum phases in the TGBs not limited at the magic angle? Here we studied electronic properties of a TGB with theta~1.64° and demonstrated that a VHS splits into two spin-polarized states flanking the Fermi energy when the VHS is close to the Fermi level. Such a result indicates that localized magnetic moments emerge in the AA-stacked regions of the TGB. Since the low-energy VHSs are quite easy to be reached in slightly TGBs, our result therefore provides a facile direction to realize novel quantum phases in graphene system.

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Yi-Wen Liu, Jia-Bin Qiao, Chao Yan, Yu Zhang, Si-Yu Li, Lin He. 2019-01-12. Magnetism near half-filling of a van Hove singularity in twisted graphene bilayer. https://doi.org/10.1103/physrevb.99.201408

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