Imaging Non-Local Magnetization Dynamics

Many fundamental processes in magnetism take place on a nanometer length and sub-picosecond time scale. An important example of such phenomena in magnetism is ultrafast, spin-polarized transport of laser-excited hot electrons, which is now being recognized as playing a crucial role for novel spintronic devices and for optically induced magnetic switching. Recent experimental examples include the demonstration of all-optical helicity dependent control of spin-polarized currents at interfaces [1 T.J. Huisman, Nature Nanotechn., doi:10.1038/nnano.2015.331 (2016).[CrossRef]], the design of novel and efficient terahertz emitters [2 T. Seifert, arXiv:1510.03729 (2015).], and nanoscale spin reversal in chemically heterogeneous GdFeCo driven by non-local transfer of angular momentum [3 C.E. Graves, Nat. Mater. 12, 293–298 (2013).[CrossRef], [PubMed], [Web of Science ®]]. In particular, for advanced information technologies with bit densities already exceeding 1 terabit per square inch with bit cell dimensions of (15 × 38 nm2) [4 R. Wood, IEEE Transaction on Magnetics 38, 1711 (2000).[CrossRef], [Web of Science ®], [CSA]], it is of fundamental importance to understand and eventually control the mechanisms responsible for optically induced spin dynamics on the nanoscale