Nematicity and competing orders in superconducting magic-angle graphene
Nematicity and competing orders in superconducting magic-angle graphene
复制标题
DOI：
10.1126/science.abc2836
复制
发表时间：
2021-04-16
期刊：
影响因子：
56.9
通讯作者：
Jarillo-Herrero, Pablo
中科院分区：
文献类型：
--
作者：
Cao, Yuan;Rodan-Legrain, Daniel;Jarillo-Herrero, Pablo
在固态系统中，强相互作用的电子经常在基态表现出多个破缺的对称性。不同序参数之间的相互作用可以产生丰富的相图。我们报道了魔角扭曲双层石墨烯(TBG)中旋转对称性破缺的缠绕相的识别。利用横向电阻测量，我们发现强各向异性相位于超导穹顶欠掺杂区上方的“楔形区”。当它与超导穹顶相交时，观察到临界温度降低。此外，超导态对方向相关的面内磁场表现出各向异性响应，揭示了整个超导穹顶的向列相有序化。这些结果表明，向列相涨落可能在魔角TBG的低温相中起重要作用。
Strongly interacting electrons in solid-state systems often display multiple broken symmetries in the ground state. The interplay between different order parameters can give rise to a rich phase diagram. We report on the identification of intertwined phases with broken rotational symmetry in magic-angle twisted bilayer graphene (TBG). Using transverse resistance measurements, we find a strongly anisotropic phase located in a "wedge" above the underdoped region of the superconducting dome. Upon its crossing with the superconducting dome, a reduction of the critical temperature is observed. Furthermore, the superconducting state exhibits an anisotropic response to a direction-dependent in-plane magnetic field, revealing nematic ordering across the entire superconducting dome. These results indicate that nematic fluctuations might play an important role in the low-temperature phases of magic-angle TBG.