论文标题
应变诱导的零能量平坦带中的电子相互作用在扭曲的双层石墨烯中
Electron interactions in strain-induced zero-energy flat band in twisted bilayer graphene near the magic angle
论文作者
论文摘要
在扭曲的双层石墨烯（TBG）中的魔法角度附近，观察到11-16-16-16-16。在TBG中几乎不可避免的异形可以修改其单粒子条带结构，并导致TBG的新型特性，而TBG到目前为止从未被认为。在这里，我们表明，在魔术角附近的TBG中，异形在两个VHS之间产生了一个新的零能量扁平频带。我们掺杂TBG以部分填充零能量的平坦带，我们观察到相关引起的缝隙约为10 MeV，从而拆分了平坦的频带。通过施加垂直磁场，观察到间隙对磁场的较大且线性的响应，这归因于当平坦带的山谷退化性通过电子电子相互作用提高时，TBG中大轨道磁矩的出现。在TBG中，每Moire Supercell的轨道磁矩被测量约15 Ub。
In the vicinity of the magic angle in twisted bilayer graphene (TBG), the two low-energy van Hove singularities (VHSs) become exceedingly narrow1-10 and many exotic correlated states, such as superconductivity, ferromagnetism, and topological phases, are observed11-16. Heterostrain, which is almost unavoidable in the TBG, can modify its single-particle band structure and lead to novel properties of the TBG that have never been considered so far. Here, we show that heterostrain in a TBG near the magic angle generates a new zero-energy flat band between the two VHSs. Doping the TBG to partially fill the zero-energy flat band, we observe a correlation-induced gap of about 10 meV that splits the flat band. By applying perpendicular magnetic fields, a large and linear response of the gap to magnetic fields is observed, attributing to the emergence of large orbital magnetic moments in the TBG when valley degeneracy of the flat band is lifted by electron-electron interactions. The orbital magnetic moment per moire supercell is measured as about 15 uB in the TBG.
