Study of Ultrafast Magnetism by THz Emission Spectroscopy

THz emission spectroscopy is a powerful tool to access ultrafast magnetization dynamics in laser-excited magnetic systems. Here, we demonstrate femtosecond terahertz magnetometry, a method that can be used to rigorously reconstruct the (sub)picosecond-timescale magnetization dynamics in photoexcited magnetic sample from the detected THz emission. Considering the propagation of the THz field from the surface of the sample to the THz electro-optic sampling unit, we establish the transfer function, which allows us to obtain the ultrafast magnetization dynamics in the laser-excited sample in a calibrated manner.