发表机构
University of Notre Dame; Stavropoulos Center for Complex Quantum Matter, University of Notre Dame; University of Texas at Dallas; National Institute for Materials Science; Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST（圣母大学; 圣母大学斯塔夫罗普洛斯复杂量子物质中心; 德克萨斯大学达拉斯分校; 国立研究开发法人物质·材料研究机构; 加泰罗尼亚纳米科学与技术研究所（ICN2），西班牙国家研究委员会与巴塞罗那科学技术研究院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文开发低温偏振敏感太赫兹纳米显微术，在双层石墨烯中观测到体光伏效应，揭示量子几何与能带结构关联，为量子材料研究提供新光学探针。
AI 中文摘要
体光伏效应（BPVE）在量子几何与非线性光-物质相互作用之间提供了直接联系，然而传统的远场测量无法将BPVE与接触和界面引起的光热电信号区分开来。在此，我们开发了具有深亚波长分辨率的低温、偏振敏感太赫兹显微镜，并将其应用于双栅极AB堆叠双层石墨烯。在带隙与太赫兹光子能量接近共振时，我们观察到增强的光电导率和空间分辨的BPVE。偏振相关测量揭示了一个特征性的二重角对称性和一个明显的位移矢量方向，两者均由晶体对称性和量子几何决定。BPVE随载流子密度和温度的变化为双层石墨烯的精细电子结构提供了灵敏的探测手段，揭示了三角翘曲和电子-空穴不对称性的特征。与理论的一致性表明，本文建立的BPVE太赫兹纳米显微术为量子材料中能带与量子几何之间的相互作用提供了一个光学透镜。
英文摘要
The bulk photovoltaic effect (BPVE) provides a direct link between quantum geometry and nonlinear light-matter interactions, yet conventional far-field measurements cannot disentangle BPVE from contact- and interface-induced photothermoelectric signals. Here we develop cryogenic, polarization-sensitive terahertz microscopy with deep-subwavelength resolution and apply it to dual-gated AB bilayer graphene. Near resonance between the band gap and terahertz photon energy, we observe enhanced optical conductivity and spatially resolved BPVE. Polarization-dependent measurements reveal a characteristic twofold angular symmetry and a distinct shift-vector direction, both governed by crystalline symmetries and quantum geometry. The evolution of BPVE with carrier density and temperature provides a sensitive probe of the fine electronic structure of bilayer graphene, revealing signatures of trigonal warping and electron-hole asymmetry. Agreement with theory demonstrates that the terahertz nanoscopy of BPVE established here offers an optical lens into the interplay between band and quantum geometry in quantum materials.
