Figure 4: Optical tuning of the ferromagnetic exchange interaction in experiment and theory.
From: Ultrafast optical tuning of ferromagnetism via the carrier density
(a) Relation between nc and the photoinduced change of the MSHG intensity at Δt=3 ps and at 10 K, extracted from Fig. 3. The line is a guide to the eye. Error bars for nc represent the s.e.m. and the uncertainty in the film thickness in determining nc from the Hall measurements. (b) Calculated change of Jex due to the modification of the RKKY interaction by the photoinduced non-equilibrium population of the 5d6s conduction band. Because of the expansion 
the data in a are directly comparable to the theory in b. (c) Sketch of the photoexcitation dynamics beyond the 3TM in low-doped Eu1−xGdxO. The photoinduced long-lived non-equilibrium carriers modify the RKKY interaction, and thus Jex. The crossed out arrow refers to photon absorption within the 5d6s conduction band, which is kinematically forbidden. For clarity, only the majority (spin-up) carriers are shown.
