Probing the local magnetization dynamics in large systems with spatial inhomogeneity

We demonstrate the multifunctionality of our new femtosecond laser scanning Kerr microscope by studying the magnetization dynamics in a wedged Fe/Gd multilayer film exhibiting a spin reorientation transition (SRT). The microscope with a high temporal and spatial resolution of < 230 f s and 210 nm, respectively, and large scanning ranges of 8 ns and 320 μm allows performing multi-parameter scans along the temporal, the three spatial, and the external magnetic field axes. From these scans we can measure local static and dynamic hysteresis loops at different delay times and positions along the wedge as well as construct spatio-temporal mapping of the magneto-optic signal at different fields. The results reveal a complex magnetization dynamics around the SRT.