Seminars Archive

The first 100 Femtoseconds: Ultrafast Dynamics in Complex Materials

Abstract
In 1999 a Nobel Prize was awarded in the field of femtochemistry for real time observation of the energy flow during breaking and forming of chemical bonds. In addition to energy conservation angular momentum plays a crucial role for many modern functional materials which are characterized by a complex interplay of charge, spin and lattice degrees of freedom. The use of fs laser excitation leads to the fascinating prospect of observing energy and angular momentum transfer between different degrees of freedom with the ultimate goal of their coherent control. This also serves to disentangle the influence of many particle interactions in materials, a remaining formidable challenge in modern physics. We recently succeeded in demonstrating that tunable polarized fs x-ray pulses are capable of probing the angular momentum dissipation in ferromagnetic model systems directly. Such studies are also of relevance for establishing the ultimate time scale for magnetic switching in future nanoscale data storage devices. First experiments at Free Electron Lasers demonstrate how also the polaronic motion of charge carriers in complex oxides can be followed in real time.