We present an element specific and spatially resolved view of magnetic domains in Co/Pt heterostructures in the extreme ultraviolet spectral range. Resonant small-angle scattering and coherent imaging with Fourier-transform holography reveal nanoscale magnetic domain networks via magnetic dichroism of Co at the M2,3 edges as well as via strong dichroic signals at the O2,3 and N6,7 edges of Pt. We demonstrate for the first time simultaneous, two-color coherent imaging at a free-electron laser facility paving the way for a direct real space access to ultrafast magnetization dynamics in complex multicomponent material systems.

We use time-resolved x-ray resonant magnetic scattering (TR-XRMS) at the Co M 2,3 and Tb O 1 edges to study ultrafast demagnetization in an amorphous Co 88 Tb 12 alloy with stripe domains. Combining the femtosecond temporal with nanometer spatial resolution of our experiment, we demonstrate that the equilibrium spin texture of the thin film remains unaltered by the optical pump pulse on ultrashort timescales (<1 ps). However, after 4 ps, we observe the onset of a significant domain wall broadening, which we attribute to a reduction of the uniaxial magnetic anisotropy of the system, due to energy transfer to the lattice. Static temperature-dependent magnetometry measurements combined with analytical modeling of the magnetic structure of the thin film corroborate this interpretation.