Extreme Domain Wall Speeds under Ultrafast Optical Excitation.

Time-resolved ultrafast EUV magnetic scattering was used to test a recent prediction of >10  km/s domain wall speeds by optically exciting a magnetic sample with a nanoscale labyrinthine domain pattern. Ultrafast distortion of the diffraction pattern was observed at markedly different timescales compared to the magnetization quenching. The diffraction pattern distortion shows a threshold dependence with laser fluence, not seen for magnetization quenching, consistent with a picture of domain wall motion with pinning sites.

Observation of Collective Molecular Dynamics in a Chalcogenide Glass: Results from X-ray Photon Correlation Spectroscopy.

The structural relaxation processes in a GeAsS molecular chalcogenide glass sample were directly studied by X-ray photon correlation spectroscopy (XPCS). XPCS was conducted at the first sharp diffraction peak at = 1.16 Å at temperatures ranging from 123 K to above the glass transition at 328 K, and the results showed two different dynamical regimes.