发表机构
University of Pennsylvania; Massachusetts Institute of Technology; National Institute of Standards and Technology（宾夕法尼亚大学; 麻省理工学院; 美国国家标准与技术研究院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文提出利用光空间色散的光生伏打效应，在无对称性破缺的中心对称晶体中隔离并测量量子度量与Berry曲率，并在1T'-MoTe2中验证，为量子几何张量提供了统一实验探针。
AI 中文摘要
Berry曲率和Bloch态的量子度量控制着广泛的现象，然而对两者的统一实验获取仍然有限。这里我们表明，光空间色散改变了二阶光电流的选择规则，在没有任何外场、磁序、界面、应变或工程对称性破缺的情况下，中心对称晶体中原本被奇偶性禁止的响应变得允许。由此产生的响应是内禀的，其权重由Bloch态的量子几何决定。传统光生伏打效应受晶体对称性约束，并将量子度量与位移矢量贡献纠缠在一起。空间色散响应反而在不同的偏振通道中隔离了量子度量与Berry曲率。在1T'-MoTe2中，我们跨越其温度驱动的Td-Weyl相变实施该方法，从同一器件中分别解析出对应量子度量与Berry曲率贡献的螺旋度偶和螺旋度奇光电流。度量主导的响应在两种相中持续存在，并展现出稳健的谱结构，该结构由第一性原理计算重现，并与动量分辨的量子度量热点相关。相反，曲率驱动的通道仅在反演对称性破缺时出现，并通过竞争性的动量空间贡献对载流子掺杂表现出强敏感性。我们的结果确立了具有空间变化光场的光生伏打效应作为在光子能量和电子填充探测激发流形不同部分的材料中获取量子几何的一般途径。
英文摘要
Berry curvature and quantum metric of Bloch states govern a wide range of phenomena, yet unified experimental access to both remains limited. Here we show that light spatial-dispersion alters the selection rules of second-order photocurrents and responses forbidden by parity become allowed in centrosymmetric crystals without any external fields, magnetic order, interfaces, strain, or engineered symmetry breaking. The resulting response is intrinsic and its weight is set by the quantum geometry of the Bloch states. Conventional photogalvanic effects are constrained by crystal symmetry and entangle the quantum metric with shift vector contributions. The spatially-dispersive response instead isolates the quantum metric and Berry curvature in distinct polarization channels. Implementing this approach in 1T'-MoTe2 across its temperature-driven transition to Td-Weyl phase, we resolve helicity-even and helicity-odd photocurrents corresponding to quantum metric and Berry curvature contributions, respectively, from the same device. The metric-dominated response persists across both phases and exhibits a robust spectral structure reproduced by first-principles calculations and linked to momentum-resolved quantum metric hotspots. In contrast, the curvature-driven channel emerges only when inversion symmetry is broken and shows strong sensitivity to carrier doping through competing momentum-space contributions. Our results establish photogalvanic effects with spatially varying optical fields as a general route to accessing quantum geometry in materials where photon energy and electronic filling probe different parts of the excitation manifold.
Comments4 figures
