Figure 3: Tuning of ultrafast spin dynamics via the control of carrier density.
From: Ultrafast optical tuning of ferromagnetism via the carrier density

Change of the MSHG intensity at 10 K for Eu1−xGdxO is shown as a function of time delay and Gd concentration. For all traces the excitation density of the pump pulse is ~130 μJ cm−2, which creates a photocarrier density Δnc~1019 cm−3. The inset shows a magnified view of the ultrafast change of the MSHG intensity for x=0.64% and x=9.63%.