Measuring magnetic excitations in microstructures using X-ray microscopy

We describe the imaging of magnetic excitation in microstructures with a photoemission electron microscope (PEEM) installed at an undulator beamline of the Swiss Light Source. The experiment uses a stroboscopic pump–probe–gate setup. A laser synchronized to the storage ring switches currents in a coplanar wave guide resulting in magnetic field pulses of 100 ps rise time and up to 80 Oe amplitude. We measure the spatial distribution of the magnetization M(r, Δt) using X-ray magnetic circular dichroism. The results allow quantitative analysis of the magnetization with better than 100 nm spatial resolution and provide information on the frequencies, shapes and the damping of magnetic eigenmodes.