Optically Induced Train of Coherent THz Transients in [co/pt]3 Multilayers

We explored the transient reflectivity of [Co/Pt] magnetic multilayer systems on the picosecond time scale. We observed that the transient Kerr ellipticity depends on the helicity of the pump pulse. In the first 100 ps after excitation, the superposition of discrete oscillation modes with frequencies up to 4 THz results in a beating response in the time domain.