Control of the Oscillatory Interlayer Exchange Interaction with   Terahertz Radiation
  The oscillatory interlayer exchange interaction between two magnetic layers separated by a metallic spacer is one of the few coherent quantum phenomena that persist at room temperature. Here we show that this interaction can be controlled dynamically by illuminating the sample (e.g. a spin valve) with radiation in the 10-100 THz range. We predict that the exchange interaction can be changed from ferromagnetic to anti-ferromagnetic (and vice versa) by tuning the amplitude and/or the frequency of the radiation. Our chief theoretical result is an expression that relates the dynamical exchange interaction to the static one that has already been extensively measured. 
Uta Meyer, Geraldine Haack, Christoph Groth and Xavier Waintal
cond-mat.mes-hall cond-mat.mtrl-sci