Ultrafast investigation and control of Dirac and Weyl semimetals
Ultrafast investigation and control of Dirac and Weyl semimetals
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DOI：
10.1063/5.0035878
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发表时间：
2021-02-21
影响因子：
3.2
通讯作者：
Weber, Chris P.
中科院分区：
文献类型：
--
作者：
Weber, Chris P.
利用亚皮秒光脉冲的超快实验在拓扑材料的研究和应用中，特别是三维狄拉克和外尔半金属的研究和应用中，将发挥重要作用。许多这些材料的特性--它们的线性能带色散、贝里曲率、费米能下接近零的态密度、对晶体和时间反演对称性的敏感性--与它们对光的亚皮秒和几皮秒响应密切相关。超快测量提供了探索激子不稳定性和瞬态光电流的机会，后者取决于Berry曲率，并可能由基本常数量化。通过Floquet效应，光脉冲可以可控地和可逆地移动、分裂、合并或间隙材料的狄拉克和外尔节点;由超快脉冲发射的相干声子提供了类似控制节点结构的替代机制。这一观点将简要总结狄拉克和外尔半金属的超快性质的研究状况，强调重要的开放问题。它将描述这些实验机会所面临的挑战，并建议需要对超快脉冲进行哪些研究，以实现其控制和照亮狄拉克和外尔半金属物理的潜力。
Ultrafast experiments using sub-picosecond pulses of light are poised to play an important role in the study and use of topological materials and, particularly, of the three-dimensional Dirac and Weyl semimetals. Many of these materials' characteristic properties-their linear band dispersion, Berry curvature, near-vanishing density of states at the Fermi energy, and sensitivity to crystalline and time-reversal symmetries-are closely related to their sub- and few-picosecond response to light. Ultrafast measurements offer the opportunity to explore excitonic instabilities and transient photocurrents, the latter depending on the Berry curvature and possibly quantized by fundamental constants. Optical pulses may, through Floquet effects, controllably and reversibly move, split, merge, or gap the materials' Dirac and Weyl nodes; coherent phonons launched by an ultrafast pulse offer alternate mechanisms for similar control of the nodal structure. This Perspective will briefly summarize the state of research on the ultrafast properties of Dirac and Weyl semimetals, emphasizing important open questions. It will describe the challenges confronting each of these experimental opportunities and suggest what research is needed for ultrafast pulses to achieve their potential of controlling and illuminating the physics of Dirac and Weyl semimetals.