High-pressure control of optical nonlinearity in the polar Weyl semimetal TaAs
High-pressure control of optical nonlinearity in the polar Weyl semimetal TaAs
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DOI：
10.1103/physrevb.106.014101
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发表时间：
2022-07
影响因子：
3.7
通讯作者：
Chen Li;Xiang Li;T. Deshpande;Xinwei Li;N. Nair;J. Analytis;D. Silevitch;T. Rosenbaum;D. Hsieh
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文献类型：
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作者：
Chen Li;Xiang Li;T. Deshpande;Xinwei Li;N. Nair;J. Analytis;D. Silevitch;T. Rosenbaum;D. Hsieh
Weyl半金属的过渡金属单晶族最近被证明表现出异常强的二阶光学非线性，这在理论上归因于它们的极性结构引起的高度不对称偏振分布。我们通过测量TaAs在压力调谐的极性到非极性结构相变中产生的光学二次谐波（SHG）来实验验证这一假设。尽管高压结构保持非中心对称，但与环境压力值相比，SHG产率降低了20 GPa，降幅超过60%。通过研究不同组的SHG磁化率张量元件的压力依赖性，我们发现产率主要由控制沿极轴响应的单个元件控制。我们的结果证实了极轴与Weyl半金属的巨大光学非线性之间的联系，并证明了压力是一种在原位调节这种效应的手段。
The transition metal monopnictide family of Weyl semimetals recently has been shown to exhibit anomalously strong second-order optical nonlinearity, which is theoretically attributed to a highly asymmetric polarization distribution induced by their polar structure. We experimentally test this hypothesis by measuring optical second harmonic generation (SHG) from TaAs across a pressure-tuned polar-to-nonpolar structural phase transition. Despite the high-pressure structure remaining noncentrosymmetric, the SHG yield is reduced by more than 60 % by 20 GPa as compared to the ambient pressure value. By examining the pressure dependence of distinct groups of SHG susceptibility tensor elements, we find that the yield is primarily controlled by a single element that governs the response along the polar axis. Our results confirm a connection between the polar axis and the giant optical nonlinearity of Weyl semimetals and demonstrate pressure as a means to tune this effect $in$ $situ$.