Ultrafast dynamics of indirect exchange interaction and transient spin current generation in a two-dimensional electron gas

We predict that a driven localized magnetic moment coupled to mobile carriers of a metal or semiconductor surface or interface generates a specific dynamics of the carrier spin density as well as a transient spin current. Numerical results illustrate the time-dependent Friedel oscillations and the associated ultrafast Ruderman-Kittel- Kasuya-Yosida (RKKY) interaction as well as the spin current generated by the impurity spin flipping. Retardation effects of the indirect exchange interaction of the impurity spins via the conduction electrons are found and discussed. Our results point to an alternative way of controlling the local magnetization on a subpicosecond time scale via appropriate tu…