Lattice Dynamics

Upon irradiation of a solid with ultrashort light pulses the energy is initially stored in the electronic system. Subsequently a variety of electron-phonon interaction processes induces atomic motion in the system which we study with ultrafast time-resolved diffraction techniques using femtosecond electron and X-ray pulses. The unique combination of atomic-scale spatial and temporal resolution allows to follow the structural evolution in laser-excited materials in real time. Using these methods we have studied coherent optical phonons in semi-metals, the excitation of incoherent lattice vibrations during the relaxation of hot electrons, ps acoustic waves in laser-heated thin films and nanostructures, and phase transitions in magnetic materials. Our research is funded by the German Research Foundation DFG in the frame of the CRC: Non-Equilibrium Dynamics of Condensed Matter in the Time Domain.