Laser‐induced magnetisation dynamics in La 0.7 Sr 0.3 MnO 3 /SrRuO 3 superlattices

Laser‐induced magnetisation dynamics of a La 0.7 Sr 0.3 MnO 3 /SrRuO 3 superlattice is studied by means of a single‐colour optical pump‐probe technique. Significant differences in the magnetisation dynamics of a superlattice with respect to the single layers of constituent materials are demonstrated. Below the Curie temperature T C of SrRuO 3 , laser‐induced ultrafast demagnetisation is found to be followed by a uniform precession of the magnetisation around its new equilibrium. The data is described within a simple model based on a displacive excitation of a precessional magnetisation dynamics. The model is shown to give a good fit to the experimental data. As the initial temperature approaches T C , the oscillations get suppressed and eventually vanish. The magnetisation dynamics is shown to depend on whether the two distinct magnetisation vectors in the superlattice are ferromagnetically or antiferromagnetically aligned. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)