Our group pursues currently two researach axes. The first one concerns the investigation of the electronic structure of materials exhibiting electron and spin correlation effects. The microscopic origin of their intriguing macroscopic phenomena of significant technological relevance are often linked to their spectrum of low-energy excitations and their relaxation dynamics. Developing a fundamental understanding is scientifically intriguing, since these phenomena involve the interplay of different fundamental interactions and the most relevant mechanism are often still not identified. Recent highlights of this research activity can be found on this page.
The second research axis is part of the rather novel field of femtomagnetism, which was stimulated by the discovery of the ultrafast demagnetization phenomenon by Eric Beaurepaire and colleagues in 1996. Despite 20 years of intense research, the scientific community remains undecided on the mechanism underlying this phenomenon of significant technological relevance. The core issue of this debate concerns the question of how the angular momentum of the ferromagnetic state is transferred out of the spin system on this ultrafast time scale. In addition to this fundamental interest, researches on femtomagnetism have revealed that magnetization can be controlled at the femtoseconde time scale. The observation of all optical switching and pure spin current could paved the way to new magnetic storage and spintronic devices. We contribute to this field by employing time resolved X-ray experiments at femtosecond pulsed X-ray sources. This enables us to add to femtosecond temporal a naturally matching nanometer spatial resolution. In addition, X-ray based techniques offer element selectivity, which allos studying selectively the dynamics of individual components of complex materials. This capability is particulary relevant for the investigation of transport and coupling phenomena between different constituents. Recent highlights of this research activity can be found on this page.