Unconventional superconductivity in magic-angle twisted trilayer graphene
Unconventional superconductivity in magic-angle twisted trilayer graphene
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DOI：
10.1038/s41535-021-00410-w
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发表时间：
2022-01-13
影响因子：
5.7
通讯作者：
Klebl, Lennart
中科院分区：
文献类型：
--
作者：
Fischer, Ammon;Goodwin, Zachary A. H.;Klebl, Lennart
魔角扭曲三层石墨烯（MATTG）最近成为一种高度可调的平台，用于研究物质的相关相，例如相关绝缘体和超导性。超导性发生在以范霍夫奇点为界的一系列掺杂水平中，这引发了关于这种材料中超导性的起源和性质的争论。在这项工作中，我们讨论了超导态 MATTG 中原子尺度相关性产生的自旋涨落的作用。我们表明，在作为掺杂 (nu) 和温度函数的相图中，向列超导区域被铁磁态包围，并且 T-c 接近 2 K 的超导圆顶出现在整数填充 nu = -2 和 nu = -3 之间。施加垂直电场增强了电子掺杂侧的超导性，这与自旋涨落谱的变化有关。我们表明，向列非常规超导性导致局部态密度的明显特征，可通过扫描隧道光谱测量检测到。
Magic-angle twisted trilayer graphene (MATTG) recently emerged as a highly tunable platform for studying correlated phases of matter, such as correlated insulators and superconductivity. Superconductivity occurs in a range of doping levels that is bounded by van Hove singularities, which stimulates the debate of the origin and nature of superconductivity in this material. In this work, we discuss the role of spin-fluctuations arising from atomic-scale correlations in MATTG for the superconducting state. We show that in a phase diagram as a function of doping (nu) and temperature, nematic superconducting regions are surrounded by ferromagnetic states and that a superconducting dome with T-c approximate to 2 K appears between the integer fillings nu = -2 and nu = -3. Applying a perpendicular electric field enhances superconductivity on the electron-doped side which we relate to changes in the spin-fluctuation spectrum. We show that the nematic unconventional superconductivity leads to pronounced signatures in the local density of states detectable by scanning tunneling spectroscopy measurements.