范德华四元氧化物中的孪晶畴

中文摘要 AI 辅助

光学各向异性是范德华材料中许多引人入胜现象的基础，包括双曲极化激元和极端双折射。沿面外方向堆叠和扭转范德华材料已成为调控这种各向异性的有力途径，但设计横向界面仍然是一个挑战。本文报道了范德华四元氧化物MgTeMoO$_6$、MnTeMoO$_6$、ZnTeMoO$_6$和CoTeMoO$_6$中的孪晶畴，这些材料具有强的面内光学各向异性和二阶非线性。这些畴在其正交晶体结构中自然形成，并延伸数百微米。作者提出，这种稳定性是通过畴壁在晶体结构中充当对角镜面来实现的，该镜面平行于(1-10)或(110)晶面，导致相邻畴之间的双折射几乎相反。通过使用偏振分辨光学显微镜、红外-可见和频产生显微镜和透射电子显微镜确定相邻畴的晶轴之间的角度，实验证实了这一假设。后者还允许估计畴壁厚度。总体而言，具有正交光学各向异性的孪晶畴的观察为利用范德华四元氧化物进行双折射波导、极化激元操控和频率转换应用开辟了新途径。

英文摘要

Optical anisotropy is the basis for many intriguing phenomena in van der Waals materials, including hyperbolic polaritons and extreme birefringence. Stacking and twisting van der Waals materials along the out-of-plane direction emerged as a powerful route to tailor this anisotropy, but designing lateral interfaces remains a challenge. Here, twin domains are reported in the van der Waals quaternary oxides MgTeMoO$_6$, MnTeMoO$_6$, ZnTeMoO$_6$, and CoTeMoO$_6$ - materials that possess strong in-plane optical anisotropy and second-order nonlinearity. The domains naturally form in their orthorhombic crystal structure and extend over hundreds of micrometers. It is proposed that this stability is achieved by the domain wall acting as a diagonal mirror plane in the crystal structure, parallel to the (1-10) or (110) crystal planes, resulting in nearly opposite birefringence between domains. This hypothesis is experimentally confirmed by determining the angle between the crystal axes of neighboring domains using polarization-resolved optical microscopy, infrared-visible sum-frequency generation microscopy, and transmission electron microscopy. The latter further allowed an estimate of the domain wall thickness. Overall, the observation of twin domains with orthogonal optical anisotropy opens new routes to use van der Waals quaternary oxides for birefringent waveguiding, polariton steering, and frequency conversion applications.

发表机构

• Fritz Haber Institute of the Max Planck Society（马克斯·普朗克学会弗里茨·哈伯研究所）
• Freie Universität Berlin（柏林自由大学）
• Wuhan National Laboratory for Optoelectronics（武汉光电国家实验室）
• Huazhong University of Science and Technology（华中科技大学）
• Optics Valley Laboratory（光谷实验室）
• Hubei Optical Fundamental Research Center（湖北光学基础研究中心）
• Max Born Institute for Nonlinear Optics and Short-Pulse Spectroscopy（马克斯·玻恩非线性光学与短脉冲光谱研究所）
• Technische Universität Dresden（德累斯顿工业大学）
• Helmholz Zentrum Dresden-Rossendorf（德累斯顿-罗斯多夫亥姆霍兹中心）

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