Ultrafast transport of laser-excited spin polarized carriers in   Au/Fe/MgO(001)
  A time domain approach to probe hot carrier-induced spin dynamics is demonstrated. The experiments are performed in epitaxial Au/Fe/MgO(001), where spin-polarized hot carriers are excited in the Fe layer by 35 fs laser pulses. They propagate to the Au surface where the transient spin polarization is detected by magneto-induced second harmonic generation. Different energies of majority and minority hot carriers excited in the exchange-split Fe band structure lead to their spindependent lifetimes in Au. Accordingly, two spin-polarized current contributions which propagate superdiffusively at different velocities result in a spin current pulse of about 100 fs duration. 
Alexey Melnikov, Ilya Razdolski, Tim O. Wehling, Evangelos Th.   Papaioannou, Vladimir Roddatis, Paul Fumagalli, Oleg Aktsip...
cond-mat.mtrl-sci