We present recent results of time-resolved x-ray photoemission electron microscopy on permalloy microstructures. The stroboscopic experiments feature a time-resolution of ⌬ ഛ 130 ps. We observe a strong influence of incoherent magnetization rotation processes, leading to a significant transient stray-field formation at the edges of the microstructure.

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Fast magnetization processes in a microstructured permalloy ring with 80 µm o.d. and 30 nm thickness have been observed by photoemission electron microscopy exploiting x-ray magnetic circular dichroism as the magnetic contrast mechanism. As a high speed probe we employed synchrotron radiation pulses at the ESRF (Grenoble) operated in 16-bunch mode, yielding photon pulses of 105 ps FWHM with a period of 176 ns. Fast magnetic field pulses have been generated by means of current pulses through coplanar waveguides with the magnetic structure being lithographically prepared on their surface. A stroboscopic pump–probe set-up with a variable time delay between the field pulse and photon pulse allowed us to take snapshots of the dynamic response of the magnetic domain structure. We observed coherent magnetization rotation during the leading edge part of the field pulse, the formation of a characteristic domain pattern (‘onion state’) in the plateau region of the pulse and the fast formation of a striped domain pattern (incoherent magnetization rotation) during the trailing edge part of the field pulse. A numerical simulation confirmed essential features of the stroboscopic image series.

We present results of a direct imaging approach to visualize the dynamics of magnetic domains on the nanosecond scale. The experiments are carried out by means of an x-ray photoemission electron microscope (X-PEEM) in a stroboscopic mode and exploit the intrinsic time structure of the synchrotron radiation delivered by the storage ring facility ESRF (Grenoble). In this way we combine the high lateral resolution of a PEEM with a subnanosecond time resolution.