AI 中文总结
研究人员通过nanoSQUID磁强计结合计算，首次直接热力学证实菱面石墨烯中存在相互作用驱动的一级拓扑量子相变，揭示了相关相的相变特性与相共存机制。
AI 中文摘要
非相互作用体系中的拓扑量子相变通过能隙的连续闭合与重新打开发生。然而，在强相互作用体系中，长期以来预测竞争有序态会驱动一级相变，尽管这一可能性在实验上仍未得到解决。近期对电中性菱面石墨烯中关联相的输运研究被解读为连续拓扑相变的证据。在此，我们利用针尖型纳米超导量子干涉器件（nanoSQUID）磁强计，直接成像了自旋轨道邻近效应诱导的菱面石墨烯量子反常霍尔（QAH）态的局域轨道磁化强度。我们首次实现了具有创纪录陈数的QAH相的实空间可视化，重建了其局域热力学能隙，并追踪了其在竞争关联态间的磁化强度演化。结合自洽哈特利-福克计算，这些测量表明，层反铁磁态、QAH态和层极化绝缘态之间的序贯相变是一级的，伴随轨道磁化强度的不连续变化。在相边界附近，我们观测到波动的磁畴，为近简并竞争有序态间的相共存提供了直接的微观证据。综上，这些观测为一级拓扑量子相变提供了首个直接热力学证据，并建立了通过相竞争与共存理解相互作用驱动拓扑量子相变的微观框架。
英文摘要
Topological quantum phase transitions in non interacting systems occur through continuous gap closing and reopening. In strongly interacting systems, however, competing ordered states have long been predicted to drive first order transitions, although this possibility has remained experimentally unresolved. Recent transport studies of correlated phases in charge neutral rhombohedral graphene were interpreted as evidence for continuous topological transitions. Here, using nanoSQUID on tip magnetometry, we directly image the local orbital magnetization of a spin orbit proximitized rhombohedral graphene quantum anomalous Hall (QAH) state. We provide the first real space visualization of a QAH phase with a record Chern number, reconstruct its local thermodynamic gap, and track the evolution of its magnetization across competing correlated states. Combined with self consistent Hartree Fock calculations, these measurements show that the sequential transitions between the layer antiferromagnetic, QAH, and layer polarized insulating states are first order, accompanied by discontinuous changes in orbital magnetization. Near the phase boundaries, we observe fluctuating magnetic domains, providing direct microscopic evidence of phase coexistence between nearly degenerate competing ordered states. Together, these observations provide the first direct thermodynamic evidence for first order topological quantum phase transitions and establish a microscopic framework for understanding interaction driven topological quantum phase transitions through phase competition and coexistence.
