Unexpected Near-Infrared to Visible Nonlinear Optical Properties from 2-D Polar Metals
Unexpected Near-Infrared to Visible Nonlinear Optical Properties from 2-D Polar Metals
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二维极性金属具有意想不到的近红外到可见非线性光学特性
DOI：
10.1021/acs.nanolett.0c03481
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发表时间：
2020
期刊：
影响因子：
10.8
通讯作者：
Fuente Duran, Ana De
中科院分区：
文献类型：
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作者：
Steves, Megan A.;Wang, Yuanxi;Briggs, Natalie;Zhao, Tian;El-Sherif, Hesham;Bersch, Brian M.;Subramanian, Shruti;Dong, Chengye;Bowen, Timothy;Fuente Duran, Ana De
描述了空气稳定的二维极性金属镓和铟的近红外-可见光二次谐波产生。二维金属的光子学性质，包括金属的最大二阶极化率（接近10 nm/V），是由两到三个原子厚的晶体薄膜的原子级结构和键合决定的。在几个原子层上，键的特征从共价键演变为金属键，使面外金属-金属键的距离改变了约10%（0.2 μ m），导致对称性破缺和介导大的非线性响应的轴向静电偶极子。晶体金属原子的两种不同取向（对应于<2 μ m的横向位移）在单独的微米级台阶中持续存在，以产生不同的谐波极化。这种强烈的原子级结构-性质相互作用表明金属光子性质可以用原子精度控制。
Near-infrared-to-visible second harmonic generation from air-stable two-dimensional polar gallium and indium metals is described. The photonic properties of 2D metals, including the largest second-order susceptibilities reported for metals (approaching 10 nm/V), are determined by the atomic-level structure and bonding of two-to-three-atom-thick crystalline films. The bond character evolved from covalent to metallic over a few atomic layers, changing the out-of-plane metal–metal bond distances by approximately ten percent (0.2 Å), resulting in symmetry breaking and an axial electrostatic dipole that mediated the large nonlinear response. Two different orientations of the crystalline metal atoms, corresponding to lateral displacements <2 Å, persisted in separate micrometer-scale terraces to generate distinct harmonic polarizations. This strong atomic-level structure–property interplay suggests metal photonic properties can be controlled with atomic precision.