Time-resolved soft X-ray microscopy of magnetic nanostructures at the P04 beamline at PETRA III

Abstract

Picosecond magnetization dynamics of small permalloy (Ni80Fe20) elements has been investigated with a new full-field transmission microscope at the soft X-ray beamline P04 of the high brilliance synchrotron radiation source PETRA III.The soft X-ray microscope generates a flat-top illumination field of 20 µm diameter using a grating condenser. A tilted nanostructured magnetic sample can be excited either by making use of a mobile synchronized femtosecond laser system or by a picosecond electric current pulse via a coplanar waveguide. The transmitted light of the sample plane is directly imaged by a micro zone plate with < 65 nm resolution onto a 2D gateable X-ray detector to select one particular bunch in the storage ring that probes the time evolution of the dynamic information successively via XMCD spectromicroscopy in a pump-probe scheme.In the experiments it was possible to generate a homogeneously magnetized state in patterned magnetic layers by a strong magnetic Oersted field pulse and directly observe the destruction and recovery of the initial flux-closure vortex domain patterns. On the rising edge of the magnetic field pulse, high velocities of a central vortex core were discovered exceeding 1 km/s.