发表机构
Massachusetts Institute of Technology; Weizmann Institute of Science; Florida State University; National Institute for Materials Science（麻省理工学院; 魏茨曼科学研究所; 佛罗里达州立大学; 国立材料研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过菱方五层石墨烯/hBN莫尔超晶格的电阻测量，揭示位移场驱动的量子相变遵循半圆关系，发现分数化量子反常霍尔绝缘体相，并估算三种分数化陈绝缘体态的输运能隙。
AI 中文摘要
分数化量子反常霍尔效应已在扭曲MoTe$_2$和菱方石墨烯/hBN莫尔超晶格中被发现。这类范德华异质结构具有栅极位移场$D$这一调节旋钮，而传统的二维电子气中的分数化量子霍尔系统则不具备该特性。$D$在调控FQAHE及其他涌现量子态中起关键作用，并为探索其量子相变提供了令人兴奋的新机遇。然而，此类相变的微观细节及温度依赖的输运性质在很大程度上仍难以捉摸。在此，我们报告了在菱方五层石墨烯/hBN莫尔超晶格中的系统性电阻测量。我们发现，位移场驱动的复合费米液体、费米液体、分数化陈绝缘体与绝缘态之间的相变可由纵向和横向电阻率（或电导率）的半圆关系描述，这在分数化量子霍尔系统中尚未被充分探索。这与相变的空间分离两相图像一致，并进一步表明一种新的绝缘体相——分数化量子反常霍尔绝缘体。通过将纵向电阻的温度依赖性与热激活模型进行比较，我们估算了三种分数化陈绝缘体态中的输运能隙大小。我们的工作揭示了分数化陈绝缘体态的量子与温度演化，为菱方石墨烯中的任意子编织和栅极定义结提供了必要背景。
英文摘要
Fractional quantum anomalous Hall effect (FQAHE) has been discovered in twisted MoTe$_2$ and rhombohedral graphene/hBN moiré superlattices. Such van der Waals heterostructures feature a tuning knob of gate displacement field $D$, which is absent from the conventional fractional quantum Hall systems in two-dimensional electron gases. $D$ plays a critical role in engineering FQAHE and other emergent quantum states and provides an exciting new opportunity to explore their quantum phase transitions. However, the microscopic details of such transitions and temperature-dependent transport have remained mostly elusive. Here we report systematic resistance measurements in rhombohedral pentalayer graphene/hBN moiré superlattices. We found that the displacement field-driven phase transitions between Composite Fermi liquid, Fermi liquid, Fractional Chern insulators, and insulating states are described by semi-circle relations of the longitudinal and transverse resistivities (or conductivities), largely unexplored in the fractional quantum Hall systems. This agrees with a spatially separated two-phase picture for the phase transitions and further indicates a new insulator phase--fractional quantized anomalous Hall insulator. By comparing the temperature-dependence of longitudinal resistance with the thermal activation model, we estimated the transport gap sizes in three fractional Chern insulator states. Our work shed light on the quantum and temperature evolutions of fractional Chern insulator states--providing necessary background for anyon-braiding and gate-defined junctions in rhombohedral graphene.
Comments27 pages, 13 figures
