<p>In a dilute two-dimensional electron gas, Coulomb interactions can stabilize the formation of a Wigner crystal<sup><CitationRef AdditionalCitationIDS="CR2" CitationID="CR1">1</CitationRef>–<CitationRef CitationID="CR3">3</CitationRef></sup>. Although Wigner crystals are topologically trivial, it has been predicted that electrons in a partially filled band can break continuous translational symmetry and time-reversal symmetry spontaneously, resulting in a type of topological electron crystal known as an anomalous Hall crystal<sup><CitationRef AdditionalCitationIDS="CR5 CR6 CR7 CR8 CR9 CR10" CitationID="CR4">4</CitationRef>–<CitationRef CitationID="CR11">11</CitationRef></sup>. Here we report signatures of a generalized version of the anomalous Hall crystal in twisted bilayer–trilayer graphene, whose formation is driven by the moiré potential. The crystal forms at a band filling of one electron per four moiré unit cells (<i>ν</i> = 1/4) and quadruples the unit-cell area, coinciding with an integer quantum anomalous Hall effect. The Chern number of the state is exceptionally tunable, and it can be switched reversibly between +1 and −1 by electric and magnetic fields. Several other topological electronic crystals arise in a modest magnetic field, originating from <i>ν</i> = 1/3, 1/2, 2/3 and 3/2. The quantum geometry of the interaction-modified bands is likely to be very different from that of the original parent band, which enables possible future discoveries of correlation-driven topological phenomena.</p>

错误:搜索内容不能为空,请输入英文关键词
错误:关键词超出字数限制,请精简
高级检索

Moiré-driven topological electronic crystals in twisted graphene

  • Ruiheng Su,
  • Dacen Waters,
  • Boran Zhou,
  • Kenji Watanabe,
  • Takashi Taniguchi,
  • Ya-Hui Zhang,
  • Matthew Yankowitz,
  • Joshua Folk

摘要

In a dilute two-dimensional electron gas, Coulomb interactions can stabilize the formation of a Wigner crystal13. Although Wigner crystals are topologically trivial, it has been predicted that electrons in a partially filled band can break continuous translational symmetry and time-reversal symmetry spontaneously, resulting in a type of topological electron crystal known as an anomalous Hall crystal411. Here we report signatures of a generalized version of the anomalous Hall crystal in twisted bilayer–trilayer graphene, whose formation is driven by the moiré potential. The crystal forms at a band filling of one electron per four moiré unit cells (ν = 1/4) and quadruples the unit-cell area, coinciding with an integer quantum anomalous Hall effect. The Chern number of the state is exceptionally tunable, and it can be switched reversibly between +1 and −1 by electric and magnetic fields. Several other topological electronic crystals arise in a modest magnetic field, originating from ν = 1/3, 1/2, 2/3 and 3/2. The quantum geometry of the interaction-modified bands is likely to be very different from that of the original parent band, which enables possible future discoveries of correlation-driven topological phenomena.