近日，美国加州理工学院Stevan Nadj-Perge团队研究了自旋轨道耦合双层石墨烯中的扭曲可编程超导电性。该项研究成果发表在2025年5月7日出版的《自然》杂志上。

近晶格匹配范德华材料层之间的相对扭转角对于与莫尔平带相关的涌现现象至关重要。然而，角度旋转控制的概念并不局限于莫尔超晶格，在莫尔超晶格中，电子直接经历与扭曲角度相关的周期性势。相反，它也可以用来诱导可编程的对称破缺扰动，以稳定所需的相关状态。

研究组通过实验证明了由二硒化钨近肟化的Bernal双层石墨烯中超导电性的“无波纹”扭曲调谐以及其他相关阶数。两种材料之间的精确对准系统地控制了诱导伊辛自旋轨道耦合（SOC）的强度，从而深刻地改变了相图。随着伊辛SOC的增加，超导电性在更高的位移场下开始，并具有更高的临界温度，达到0.5 K。

在主超导圆顶和强伊辛SOC极限内，研究组发现了一种不寻常的相变，其特征是在三角翘曲的费米袋之间空穴向列重新分布，并增强了对平面内磁场的弹性。超导行为在理论上与对称破缺费米袋之间带间相互作用的突出作用是相容的。此外，研究组还发现了两个额外的超导区域，其中一个从谷间相干正常态下降，并显示出超过40的泡利极限违反率，这是所有已知超导体中最高的。该研究结果提供了对超清洁石墨烯超导体的见解，并强调了在广泛的范德华异质结构中利用无波纹扭曲工程的潜力。

附：英文原文

Title: Twist-programmable superconductivity in spin–orbit-coupled bilayer graphene

Author: Zhang, Yiran, Shavit, Gal, Ma, Huiyang, Han, Youngjoon, Siu, Chi Wang, Mukherjee, Ankan, Watanabe, Kenji, Taniguchi, Takashi, Hsieh, David, Lewandowski, Cyprian, von Oppen, Felix, Oreg, Yuval, Nadj-Perge, Stevan

Issue&Volume: 2025-05-07

Abstract: The relative twist angle between layers of near-lattice-matched van der Waals materials is critical for the emergent phenomena associated with moiré flat bands1,2,3. However, the concept of angle rotation control is not exclusive to moiré superlattices in which electrons directly experience a twist-angle-dependent periodic potential. Instead, it can also be used to induce programmable symmetry-breaking perturbations with the goal of stabilizing desired correlated states. Here we experimentally demonstrate ‘moiréless’ twist-tuning of superconductivity together with other correlated orders in Bernal bilayer graphene proximitized by tungsten diselenide. The precise alignment between the two materials systematically controls the strength of induced Ising spin–orbit coupling (SOC), profoundly altering the phase diagram. As Ising SOC is increased, superconductivity onsets at a higher displacement field and features a higher critical temperature, reaching up to 0.5K. Within the main superconducting dome and in the strong Ising SOC limit, we find an unusual phase transition characterized by a nematic redistribution of holes among trigonally warped Fermi pockets and enhanced resilience to in-plane magnetic fields. The superconducting behaviour is theoretically compatible with the prominent role of interband interactions between symmetry-breaking Fermi pockets. Moreover, we identify two additional superconducting regions, one of which descends from an inter-valley coherent normal state and shows a Pauli-limit violation ratio exceeding 40, among the highest for all known superconductors4,5,6,7. Our results provide insights into ultraclean graphene superconductors and underscore the potential of utilizing moiréless-twist engineering across a wide range of van der Waals heterostructures.

DOI: 10.1038/s41586-025-08959-3

Source: https://www.nature.com/articles/s41586-025-08959-3