Research

The group’s research focus lies in the field of ultrafast phenomena in modern solids, ranging from strongly correlated electron systems, multi-ferroics, superconductors to organic semiconductors. 

In many of these solid state systems the material’s functional properties are believed to be controlled by the interaction/interplay between the different subsystems (electrons, spin, crystal lattice). To study the interplay/coupling between various degrees of freedom we use femtosecond time-resolved techniques. In a typical experiment a femtosecond optical pulse is used to drive the system out of equilibrium, while the suitably delayed optical (from Terahertz to X-ray range) or electron pulse is used to make snapshots of the state at a given time after perturbation. In such a way movies showing e.g. the time-evolution of the electronic distribution function or the motion of the crystal lattice can be recorded. 

By tracking different excitations in real-time we can clarify their role in the functional properties of the material/system under scrutiny. Importantly, experiments can be performed both in the low excitation limit, where the system is close to the thermal equilibrium, as well as in the strong excitation regime. In the latter case various phase transition can be optically driven, enabling both new insights into these materials, as well as the external control of their functional properties.

Several experimental techniques are being developed, optimized and utilized, ranging from time-resolved THz spectroscopy, enabling access to low energy excitations, to femtosecond electron diffraction, where atomic motion is investigated on the femtosecond timescale.