Abstract:

The lifetime of excited electrons in metals and semiconductors has been investigated by means of the time- and spin-resolved two-photon photoemission spectroscopy (TR-2PPE). For ferromagnetic materials, these studies have proven the importance of screening effects and the spin-dependent electron density of state with respect to the different electronic relaxation channels. In addition, an important aspect of the dynamics of hot electron damping is the role of spin-flip processes including Stoner excitations and spin-wave emission. In semiconductors we have exploited the possibility of optical excitation of spin polarized electrons using circularly polarized light of an ultrashort pulsed laser system. We have determined the temporal evolution of the energy, momentum and spin behavior of the excited electrons on a femtosecond timescale on a GaAs/metal interface and compared our results with equivalent Faraday rotation measurements.
 
 
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