发表机构
Tsung-Dao Lee Institute, Shanghai Jiao Tong University; School of Physics and Astronomy, Shanghai Jiao Tong University; University of Tennessee; Max Planck Institute for Chemical Physics of Solids; National Institute for Materials Science; Hefei National Laboratory; Wuhan University; Southern University of Science and Technology（上海交大东京大学研究院; 上海交通大学物理与天文学院; 田纳西大学; 马克斯·普朗克固体化学物理研究所; 物质材料研究机构; 合肥国家实验室; 武汉大学; 南方科技大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究以菱面五角石墨烯为对象，通过量子振荡测量明确其费米面拓扑的Lifshitz跃迁，揭示手性超导性与维格纳晶相等竞争，确定费米面拓扑是手性超导性的关键控制参数。
AI 中文摘要
菱面多层石墨烯具有独特的低能电子结构，其中强库仑相互作用与非平凡量子几何相互交织，产生奇异量子态。近期实验报道了电子掺杂菱面多层石墨烯的自旋与谷极化区域内存在手性超导性的特征。本文绘制了菱面五角石墨烯中手性超导性周围的正常态费米学。量子振荡测量揭示了电控Lifshitz跃迁，发生在单连通圆形四金属费米面与环形四金属费米面之间。Lifshitz边界本身随垂直磁场移动，这与低能带强动量相关的轨道磁矩一致。从两侧接近该跃迁时，电子有效质量显著增强，意味着形成近无色散的带底和大幅降低的动能尺度。这种奇异的电子结构产生了极强的不稳定性区域，其中手性超导性与维格纳晶相及重入量子霍尔态竞争。特别地，两个具有轨道时间反演对称性破缺特征的超导区域位于Lifshitz边界两侧，且具有相当的转变温度，但环形侧的态被小得多的垂直磁场抑制。计算发现，两个母体费米面具有相当的手性配对倾向，同时环形态产生低得多的轨道-塞曼对破坏尺度和额外的有限动量配对倾向。这些结果确定费米面拓扑是菱面石墨烯中手性超导性的关键控制参数。
英文摘要
Rhombohedral multilayer graphene hosts a distinctive low-energy electronic structure in which strong Coulomb interactions and nontrivial quantum geometry intertwine to generate exotic quantum states. Recent experiments reported signatures of chiral superconductivity in electron-doped rhombohedral multilayer graphene within the spin- and valley-polarized regime. Here we map the normal-state fermiology surrounding chiral superconductivity in rhombohedral pentalayer graphene. Quantum oscillation measurements reveal an electrically controlled Lifshitz transition between a simply-connected circular quarter-metal Fermi surface and an annular quarter-metal Fermi surface. The Lifshitz boundary itself shifts with perpendicular magnetic field, consistent with the strongly momentum-dependent orbital magnetic moment of the low-energy band. Approaching the transition from either side, the electron effective mass becomes strongly enhanced, implying the formation of a nearly dispersionless band bottom and a strongly reduced kinetic-energy scale. This singular electronic structure produces a regime of exceptionally strong instability in which chiral superconductivity competes with Wigner crystalline phases and reentrant quantum Hall states. In particular, two superconducting regions with signatures of orbital time-reversal-symmetry breaking lie on opposite sides of the Lifshitz boundary and have comparable transition temperatures, yet the annular-side state is suppressed by a substantially smaller perpendicular magnetic field. Our calculation finds comparable chiral pairing tendencies on the two parent Fermi surfaces while producing a much lower orbital-Zeeman pair-breaking scale and an additional finite-momentum pairing tendency for the annular state. These results identify Fermi-surface topology as a key control parameter for chiral superconductivity in rhombohedral graphene.
