Subpicosecond Magneto-Optical Response Probed By The Kerr Rotation Technique In Pbi2 Film

The ultrafast optical dynamics in solution-processed PbI2 film on quartz substrate around the band edge have been systematically studied by transient reflectance spectroscopy and femtosecond resolvedKerr rotation spectroscopy at room temperature. The Kerr rotation angle shows a maximum at the excitonic photobleaching peak and increases with the pump fluence until reaching a saturation value of similar to 0.8 deg (similar to 4 deg/mu m), which is on the same order as that for CH3NH3PbI3 perovskite film. The spin lifetime gradually decreases from 2.24 to 0.48 ps when increasing thepump fluence from13 to 234 mu J/cm(2), which is attributed to the strong spin-orbital coupling and the dominance of the Elliot-Yafet process in spin relaxation. Our findings suggest that PbI2 film is a promising candidate for ultrafast spin switching with a subpicosecond time scale and optical isolator in optical communications owing to the giant rotation angle. (C) 2021 Optical Society of America