发表机构
Institute of Science and Technology Austria; King Fahd University of Petroleum and Minerals; Interdisciplinary Research Center (IRC) for Advanced Materials, King Fahd University of Petroleum and Minerals; King Abdullah University of Science and Technology; Center for Renewable Energy and Storage Technologies, Division of Physical Science and Engineering, King Abdullah University of Science and Technology; Aarhus University（科学技术奥地利研究所; 法赫德国王石油与矿产大学; 法赫德国王石油与矿产大学先进材料跨学科研究中心; 阿卜杜拉国王科技大学; 阿卜杜拉国王科技大学物理科学与工程学部可再生能源与储能技术中心; 奥胡斯大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过二维太赫兹克尔效应光谱，揭示铅卤化物钙钛矿中太赫兹驱动的晶格动力学主要经由声子介导的非谐耦合，而非直接光激发，并发现强二次耦合暗示非常规电子-声子修饰。
AI 中文摘要
我们利用二维太赫兹克尔效应光谱技术，探究了甲基铵铅溴CH$_3$NH$_3$PbBr$_3$中太赫兹驱动晶格动力学的微观起源。实验分析能够区分竞争性的非线性激发机制，并揭示主导路径是声子介导的而非纯光子过程。具体而言，我们认为通常观测到的1.15太赫兹拉曼活性$A_g$模并非由太赫兹电场直接激发，而是通过立方非谐耦合至0.68太赫兹的红外活性声子而产生。此外，1.36太赫兹处的卫星特征被识别为同一红外活性声子的双声子拉曼响应。涉及红外活性声子的强二次耦合的观测表明，铅卤化物钙钛矿中存在一种非常规的电子-声子修饰形式。
英文摘要
We explore the microscopic origin of THz-driven lattice dynamics in methylammonium lead bromide CH$_3$NH$_3$PbBr$_3$ using two-dimensional THz Kerr-effect spectroscopy. The analysis of the experiment enables discrimination between competing nonlinear excitation mechanisms and reveals that the dominant pathway is phonon-mediated rather than purely photonic. In particular, we argue that the commonly observed 1.15~THz Raman-active $A_g$ mode is not excited directly by the THz electric field. Instead, it emerges through cubic anharmonic coupling to an infrared-active phonon at 0.68~THz. Furthermore, a satellite feature at 1.36~THz is identified as a two-phonon Raman response of the same infrared-active mode. The observation of strong quadratic coupling involving the infrared-active phonon suggests an unconventional form of electron-phonon dressing present in lead-halide perovskites.
