Speaker
Description
Ultrafast optical demagnetization is a phenomena whose origins have yet to be completely understood. One challenge in studying this phenomena is the low availability of femtosecond light sources in the XUV and X-ray regimes. By exploiting the process of High Harmonic Generation (HHG) in argon, we have developed a high-flux, table-top femtosecond XUV source. We use it for probing ultrafast optical demagnetization at the M-edge of cobalt through a pump-probe system. First, a femtosecond, infrared pump pulse demagnetizes the sample. Then, a XUV probe pulse illuminates the sample, where small-angle X-ray scattering on magnetic domains allows for the observation of contrast due to the X-ray magnetic circular dichroism effect. This scheme allows us to recover demagnetization curves for different pump wavelengths ranging from 1800nm to 400nm. At 800nm, we also produce demagnetization curves for various pump durations.
