  Time-resolved x-ray magnetic circular dichroism (XMCD) enables a unique
spectroscopic view on complex spin and charge dynamics in multi-elemental
magnetic materials. So far, its application in the soft-x-ray range has been
limited to synchrotron-radiation sources and free-electron lasers. By combining
a laser-driven plasma source with a magnetic thin-film polarizer, we generate
circularly polarized photons in the soft x-ray regime, enabling the first XMCD
spectroscopy at the Fe L edges in a laser laboratory. Our approach can be
readily adapted to other transition metal L and rare earth M absorption edges
and with a temporal resolution of < 10 ps, a wide range of ultrafast
magnetization studies can be realized.
