[论文解读] Twist-angle evolution from valley-polarized fractional topological phases to valley-degenerate superconductivity in twisted bilayer MoTe2

Zheng Sun, Fan Xu+17 more|arXiv (Cornell University)|Mar 17, 2026

Topological Materials and Phenomena被引用 0

一句话总结

这篇论文绘制了扭转双层MoTe2中的扭角如何推动从谷极化的分数量子拓扑相到谷简并的超导性的演变，连接了拓扑、对称性破缺与超导性。

ABSTRACT

Moiré superlattices formed by semiconducting transition metal dichalcogenides (TMDs) provide a highly tunable platform for investigating strongly correlated and topological quantum phases. As a prototypical example, twisted bilayer MoTe2 (tMoTe2) has been shown to host fractional topological phases, such as zero-field fractional Chern insulators (FCIs) exhibiting fractional quantum anomalous Hall (FQAH) effects. However, how these correlated topological phases evolve with twist angle and compete with other quantum phases in tMoTe2 remains largely unexplored. Here we report a systematic transport study of twist-angle-dependent phase diagrams in tMoTe2 across a range of 3.8°-5.78°, revealing an evolution from fractionalized states of matter with spontaneous valley polarization to valley-degenerate superconductivity. At relatively small twist angles, partially-filled Chern bands of tMoTe2 host FQAH states following the Jain sequence, together with signatures of an anomalous composite Fermi liquid at moiré hole filling factor νh = 1/2. Increasing twist angle progressively suppresses fractional topological phases and reconstructs the half-filled Chern band into symmetry-breaking integer Chern insulating states. At νh = 1, we observe a transition from robust integer quantum anomalous Hall (IQAH) insulators at small angles to displacement-field-tuned, topologically trivial correlated insulators at larger angles. Remarkably, at a twist angle of 5.78°, superconductivity emerges adjacent to the correlated insulating phase, with a phase diagram closely resembling that recently reported in twisted bilayer WSe2 (tWSe2). Our results uncover a unified twist-angle-driven phase evolution linking fractional topology, symmetry breaking, magnetic order, and superconductivity, providing new insight into the emergent quantum phenomena in moiré systems.

研究动机与目标

• 研究扭转角在扭转双层MoTe2 (tMoTe2) 中对相关拓扑和超导相的影响。
• 识别角度增大时从分数量子霍尔态向超导性的演变。
• 在不同角度下考察谷极化、对称性破缺与超导倾向之间的竞争。

提出的方法

• 在 tMoTe2 中对扭转角从 3.8° 到 5.78° 进行系统的传输测量。
• 对部分充填的 Chern 能带中的分数量拓扑态和 FQAH 效应进行现场表征。
• 分析莫尔填充因子，包括 νh = 1/2 与 νh = 1，以绘制相界。
• 将观测到的相演化与相关莫尔系统（如 tWSe2）中的已知行为进行比较。

实验结果

研究问题

• RQ1 随着扭转角从较小值增大，tMoTe2 中的分数量拓扑相如何演变？
• RQ2 驱动从谷极化拓扑态向谷简并超导性的转换的机制是什么？
• RQ3 νh = 1/2 与 νh = 1 如何与不同角度下的观测相对应？
• RQ4 对称性破缺、磁序和位移场在稳定或抑制这些相中起到怎样的作用？

主要发现

• 在较小扭角时，部分充填的 Chern 能带承载 FQAH 态，遵循 Jain 序列。
• 在莫尔空穴填充因子 νh = 1/2 时观测到异常复合费米液体。
• 增加扭角抑制分数量拓扑相，并将半充填的 Chern 能带重构为具有对称性破缺的整数量子 Chern 绝热体。
• 在 νh = 1 时，随着角度增大，从强鲁棒的 IQAH 绝热体向位移场控制的、拓扑上平凡的相关绝热体转变。
• 在扭角为 5.78° 时，超导性在相关绝热相邻近处出现，类似于在 tWSe2 中的行为。
• 结果表明存在一个统一的扭角驱动演化，将分数量拓扑、对称性破缺、磁序与超导性联系起来。