Nano-Bio Spectroscopy Group and ETSF, Universidad del País Vasco, CFM CSIC-UPV/EHU, San Sebastián 20018, Spain.
Max Planck Institute for the Structure and Dynamics of Matter and Center for Free Electron Laser Science, Hamburg 22761, Germany.
Nat Commun. 2017 Jan 17;8:13940. doi: 10.1038/ncomms13940.
Tuning and stabilizing topological states, such as Weyl semimetals, Dirac semimetals or topological insulators, is emerging as one of the major topics in materials science. Periodic driving of many-body systems offers a platform to design Floquet states of matter with tunable electronic properties on ultrafast timescales. Here we show by first principles calculations how femtosecond laser pulses with circularly polarized light can be used to switch between Weyl semimetal, Dirac semimetal and topological insulator states in a prototypical three-dimensional (3D) Dirac material, NaBi. Our findings are general and apply to any 3D Dirac semimetal. We discuss the concept of time-dependent bands and steering of Floquet-Weyl points and demonstrate how light can enhance topological protection against lattice perturbations. This work has potential practical implications for the ultrafast switching of materials properties, such as optical band gaps or anomalous magnetoresistance.
调控和稳定拓扑状态，如外尔半金属、狄拉克半金属或拓扑绝缘体，正在成为材料科学的主要课题之一。多体系统的周期性驱动为在超快时间尺度上设计具有可调电子特性的弗洛凯态物质提供了一个平台。在这里，我们通过第一性原理计算表明，圆偏振飞秒激光脉冲如何能够在典型的三维（3D）狄拉克材料 NaBi 中在 Weyl 半金属、狄拉克半金属和拓扑绝缘体状态之间进行切换。我们的发现是普遍的，适用于任何 3D 狄拉克半金属。我们讨论了时变能带和 Floquet-Weyl 点的控制的概念，并展示了光如何增强对晶格扰动的拓扑保护。这项工作对于材料性质的超快切换具有潜在的实际意义，例如光学带隙或反常磁阻。
