  A detailed understanding of the different mechanisms being responsible for
terahertz (THz) emission in ferromagnetic (FM) materials will aid in designing
efficient THz emitters. In this report, we present direct evidence of THz
emission from single layer Co$_{0.4}$Fe$_{0.4}$B$_{0.2}$ (CoFeB) FM thin films.
The dominant mechanism being responsible for the THz emission is the anomalous
Hall effect (AHE), which is an effect of a net backflow current in the FM layer
created by the spin-polarized current reflected at the interfaces of the FM
layer. The THz emission from the AHE-based CoFeB emitter is optimized by
varying its thickness, orientation, and pump fluence of the laser beam. Results
from electrical transport measurements show that skew scattering of charge
carriers is responsible for the THz emission in the CoFeB AHE-based THz
emitter.
