Fig. 1. Ultrafast OISTR in Fe₅₀Ni₅₀.

(A) Schematic overview of the OISTR effect in Fe₅₀Ni₅₀. The optical excitation by the IR pump leads to an effective spin transfer from the occupied Ni minority channel into the Fe minority channel. Note that other excitations are also possible, and significant OISTR can only be expected if such a spin transfer transition dominates the full excitation process. (B) Projected density of states (DOS) calculation for Fe₅₀Ni₅₀ for Fe (green) and Ni (blue) demonstrating the favorable spin transfer from Ni to Fe in the minority channel. (C and D) TD-DFT calculations of the difference of the transient occupation compared with the unexcited case in the minority channels of Ni (C) and Fe (D) at characteristic time steps demonstrating the OISTR effect. In Ni at energies between 0.5 and 3 eV below the Fermi level, a negative signal arises corresponding to a loss of minority electrons, while a simultaneous positive signal correlating to minority spin gain is visible in Fe at equivalent energies above the Fermi level.