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【摘要】

The coherent electric field drive by photoelectric fields have been attracted in recent years [1,2]. However, it has been very difficult to observe photoelectric field-driven phenomena in solids because the electron scattering time of ordinary materials is very fast, on the order of 10 fs, and electron scattering disturbs the coherence between light and electrons. Therefore, we have attempted to observe photoelectric field driven phenomena in the THz frequency band (~1 ps) by using Weyl semimetals, which have relatively long electron scattering times (several hundred fs to several ps).
We have measured the excitation intensity dependence of the high power THz pump/THz reflection spectra in the ferromagnetic Wely semimetal Co3Sn2S2 with a Weyl band of a few ten meV at 7 K. High power THz pulses were generated by Ti-sapphire laser (1.55 eV, 1 mJ, 1 kHz, 70 fs) in a LiNO3 crystal using the tilted wave front method. 
[1] T. Higuchi, et al., Nature 550, 224–228 (2017).
[2] Y. Kawakami, et al., Nat. Commun. 11, 4138 (2020).