发表机构
University of Pennsylvania; Indian Institute of Science Education and Research, Pune; Drexel University（宾夕法尼亚大学; 印度科学教育研究所浦那分校; 德雷塞尔大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过三阶非线性输运在RbV$_3$Sb$_5$中探测隐藏环流相，发现约35 K处的三次响应异常，并证明量子度量四极矩驱动该现象，为探测时间反演对称破缺电子相提供了灵敏探针。
AI 中文摘要
在kagome金属AV$_3$Sb$_5$（A=K、Rb或Cs）中，已提出一种具有可能环流序的隐藏低温相，但其实验特征仍然微妙且间接。在这里，我们利用三阶非线性输运来探测RbV$_3$Sb$_5$中的这一隐藏相。在约35 K时，纵向三次响应出现强烈的扭结和显著的方向各向异性，并强烈偏离常见的弛豫时间标度，而横向三次响应在同一温度下获得一个磁场奇分量。它们的同时出现将三次谐波响应确定为具有时间反演对称性破缺的低温电子重构的敏感标记。至关重要的是，我们发现量子度量四极矩直接贡献于纵向三阶响应。在环流电荷密度波模型中，其方向选择性增强捕捉到了观测到的角度重构。我们的工作展示了高阶非线性输运如何将电子对称性和量子度量的细微变化转化为量子材料中可测量的电学信号，这对于研究复杂电子相具有重要意义。
英文摘要
A hidden low-temperature phase with possible loop-current order has been proposed in the kagome metals AV$_3$Sb$_5$ (A=K, Rb or Cs), but its experimental signatures remain subtle and indirect. Here, we use third-order nonlinear transport to probe this hidden phase in RbV$_3$Sb$_5$. At ~35 K, the longitudinal cubic response develops a strong kink and pronounced directional anisotropy with a strong departure from common relaxation time scaling, while the transverse cubic response acquires a magnetic field-odd component at the same temperature. Their coincident onset identifies the third-harmonic response as a sensitive marker of the low-temperature electronic reconstruction with time-reversal broken symmetry. Crucially, we find that the quantum metric quadrupole contributes directly to the longitudinal third-order response. In a loop-current charge-density-wave model, its direction selective enhancement captures the observed angular reconstruction. Our work shows how higher-order nonlinear transport translates subtle changes in electronic symmetry and quantum metric into measurable electrical signatures in quantum materials that is important for studying complex electronic phases of matter.
