Department of Physics, Columbia University, New York, NY 10027, USA.
Department of Physics, Harvard University, Cambridge, MA 02138, USA.
Science. 2022 Apr 8;376(6589):193-199. doi: 10.1126/science.abk1895. Epub 2022 Apr 7.
Magic-angle twisted trilayer graphene (TTG) has recently emerged as a platform to engineer strongly correlated flat bands. We reveal the normal-state structural and electronic properties of TTG using low-temperature scanning tunneling microscopy at twist angles for which superconductivity has been observed. Real trilayer samples undergo a strong reconstruction of the moiré lattice, which locks layers into near-magic-angle, mirror symmetric domains comparable in size with the superconducting coherence length. This relaxation introduces an array of localized twist-angle faults, termed twistons and moiré solitons, whose electronic structure deviates strongly from the background regions, leading to a doping-dependent, spatially granular electronic landscape. The Fermi-level density of states is maximally uniform at dopings for which superconductivity has been observed in transport measurements.
魔角扭曲三层石墨烯（TTG）最近成为了工程强关联平带的平台。我们使用低温扫描隧道显微镜研究了在观察到超导现象的扭转角下 TTG 的正常态结构和电子性质。真正的三层样品经历了莫尔晶格的强烈重构，将层锁定在近魔角、镜像对称的畴中，其大小与超导相干长度相当。这种弛豫引入了一系列局域扭转角缺陷，称为扭曲子和莫尔孤子，它们的电子结构与背景区域有很大的偏离，导致掺杂依赖性的、空间颗粒状的电子景观。在输运测量中观察到超导现象的掺杂下，费米能级态密度最大程度上保持均匀。
