Chiral terahertz wave emission from the Weyl semimetal TaAs
Chiral terahertz wave emission from the Weyl semimetal TaAs
复制标题
外尔半金属 TaAs 的手性太赫兹波发射
DOI：
10.1038/s41467-020-14463-1
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发表时间：
2020-02-05
影响因子：
16.6
通讯作者：
Qi, J.
中科院分区：
文献类型：
--
作者：
Gao, Y.;Kaushik, S.;Qi, J.
外尔半金属拥有不同的手征性和自旋纹理的手征费米子。这些手征费米子的光激发可以引起奇异载流子响应，从而导致新的光学现象。在这里，我们发现强大的相干太赫兹辐射外尔半金属砷，这是一个独特的宽带源的手征太赫兹波。太赫兹辐射的偏振控制是通过光电流效应调节超快光电流的光激发来实现的。在近红外区，由于占主导地位的圆形光电流效应的光子能量依赖的非热电流可以归因于带速度的根本变化时，手征外尔费米子被激发在倾斜的各向异性外尔锥和大量的散装带之间的选择性光学跃迁。我们的研究结果提供了一个设计概念，创造手性光子源使用量子材料，并开辟了新的机会，开发超快光电子学使用外尔物理。
Weyl semimetals host chiral fermions with distinct chiralities and spin textures. Optical excitations involving those chiral fermions can induce exotic carrier responses, and in turn lead to novel optical phenomena. Here, we discover strong coherent terahertz emission from Weyl semimetal TaAs, which is demonstrated as a unique broadband source of the chiral terahertz wave. The polarization control of the THz emission is achieved by tuning photoexcitation of ultrafast photocurrents via the photogalvanic effect. In the near-infrared regime, the photon-energy dependent nonthermal current due to the predominant circular photogalvanic effect can be attributed to the radical change of the band velocities when the chiral Weyl fermions are excited during selective optical transitions between the tilted anisotropic Weyl cones and the massive bulk bands. Our findings provide a design concept for creating chiral photon sources using quantum materials and open up new opportunities for developing ultrafast opto-electronics using Weyl physics.