Investigating Coherent Magnetization Control with Ultrashort THz Pulses

Coherent terahertz control of magnetization dynamics is an area current interest due to its great potential for the realization on ultrafast timescales in commercial devices. Here we report experiment realized at THz beamline free electron laser FLASH DESY which offers a tunable radiation source and spontaneously synchronized free-electron X-ray pulses resonantly probe state ferromagnetic film. In this proof-of-principle experiment, have excited thin Permalloy film different wavelengths recorded induced with photons tuned Ni M2,3 absorption edge. For pump including higher orders undulator observed demagnetization dynamics, precise shape depended employed fundamental wavelength source. Analyzing detail, can reconstruct temporal profile electric field pulse. This new method in-situ diagnostic will help researchers adjust pulse characteristics as needed, example, future studies coherent dynamics.