レーザー励起光電子による磁気円二色性

抄録

  We report magnetic circular dichroism (MCD) on ultrathin films using lasers as excitation sources. By using threshold photoemission, we can obtain high MCD asymmetry. On the other hand, when the laser photon energy is far away from the threshold, the MCD asymmetry is small. The MCD asymmetry depends also on the magnetization, and MCD is larger for the perpendicularly magnetized films. The reason for the enhanced MCD asymmetry near the threshold is spontaneous momentum and energy selection in the photoelectron excitation. The MCD dependence on the magnetization direction is explained by the polarization change of reflected light, which is negligible for x-ray MCD. Also shown is the photoemission electron microscope observation of magnetic domains using lasers.