Orderly disorder in magic-angle twisted trilayer graphene
Orderly disorder in magic-angle twisted trilayer graphene
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DOI：
10.1126/science.abk1895
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发表时间：
2021-09
期刊：
影响因子：
56.9
通讯作者：
Simon Turkel;Joshua Swann;Ziyan Zhu;Maine Christos;K. Watanabe;T. Taniguchi;S. Sachdev;M. Scheurer;E. Kaxiras;C. Dean;A. Pasupathy
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作者：
Simon Turkel;Joshua Swann;Ziyan Zhu;Maine Christos;K. Watanabe;T. Taniguchi;S. Sachdev;M. Scheurer;E. Kaxiras;C. Dean;A. Pasupathy
魔角扭曲三层石墨烯（TTG）最近已经成为一个平台，工程师强相关的平带。我们揭示了正常状态下的结构和电子特性的TTG使用低温扫描隧道显微镜在扭曲角，已观察到超导性。真实的三层样品经历了莫尔晶格的强烈重构，其将层锁定成在尺寸上与超导相干长度相当的近魔角、镜像对称域。这种弛豫引入了一系列局部扭转角故障，称为扭曲和莫尔孤子，其电子结构强烈偏离背景区域，导致掺杂依赖的，空间颗粒状的电子景观。费米能级态密度在掺杂处最均匀，在输运测量中观察到超导性。描述放大到三层石墨烯堆叠和扭曲石墨烯层相对于彼此可以导致奇异的传输效应。最近，在石墨烯三层中观察到了超导性，其中顶层和底层相对于中间层以相同的“神奇”角度扭曲。Turkel等人使用扫描隧道显微镜来仔细观察堆叠结构。他们发现，顶层和底层之间的微小错位会导致晶格重新排列成三角形结构域的图案。畴具有魔角扭曲的三层结构，并由线缺陷和点缺陷的网络分开。-JS扫描隧道显微镜揭示了莫尔材料中的晶格重构。
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. Description Zooming into trilayer graphene Stacking and twisting graphene layers with respect to each other can lead to exotic transport effects. Recently, superconductivity was observed in graphene trilayers in which the top and bottom layers are twisted with respect to the middle layer by the same, “magic” angle. Turkel et al. used scanning tunneling microscopy to take a closer look into the stacking structure. They found that a small misalignment between the top and bottom layers caused the lattice to rearrange itself into a pattern of triangular domains. The domains had a magic-angle twisted trilayer structure and were separated by a network of line and point defects. —JS Scanning tunneling microscopy reveals lattice reconstruction in a moire material.