Subpicosecond magneto-optical response probed by the Kerr rotation technique in PbI2 film

Abstract

The ultrafast optical dynamics in solution-processed P b I 2 film on quartz substrate around the band edge have been systematically studied by transient reflectance spectroscopy and femtosecond resolved Kerr 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 ∼ 0.8 d e g ( ∼ 4 d e g / µ m ), which is on the same order as that for C H 3 N H 3 P b I 3 perovskite film. The spin lifetime gradually decreases from 2.24 to 0.48 ps when increasing the pump fluence from 13 to 234 µ J / c m 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 P b I 2 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.