Ultrafast Spectroscopy
Our interest is to understand the origin of the physical properties of modern materials. The goal is to increase the fundamental knowledge in the physics of solid state, to help designing new materials with defined properties and possibly to control material and their properties with external stimuli like light pulse or mechanical strain.
For this purpose, we are using a variety of experimental techniques that grant us access to the electronic structure of materials, in our laboratory at the University of Fribourg
Using angle-resolved photoemission spectroscopy, we measure the electronic structure in reciprocal space. This is the most powerful method to study the organisation of electrons in their different energy levels.
Using scanning tunneling microscopy, we measure the distribution of electrons in real space. This electronic microscopy can be performed down to the atomic length scale. Spectroscopy can also be done in real space with this resolution.
Using X-ray photoemission spectroscopy, we can resolve the chemical composition of samples. We can also obtain information on the types of chemical bonds that take place in solid state matter. We offer this service for internal and external collaborations.
All these techniques are surface sensitive, because of the small escape depth of electrons.
In addition, we also use Resonant Inelastic X-ray Scattering to study the electronic and magnetic structure of materials using synchrotron radiation. This is a powerful technique that offers more bulk sensitivity.
Our group is also expert in the use of time-resolved spectroscopies using a stroboscopic pump-probe scheme: an intense pump pulse (specific to the material investigated) excites matter out of equilibrium and a probe pulse (specific to the used spectroscopy) arriving a few tens of femtosecond later performs the desired spectroscopy. With ultrafast lasers, we study the real time dynamics of new materials and resolve the evolution of electrons on the femtosecond time scale. With this approach, we can further understand the complex interplay of the different degrees of freedom that are the key actors in solid state matter: electrons, atoms and spins. This spectroscopic probe gives access to the transient electronic structure of complex materials.
Our research activities focuses on a class of materials called strongly electron correlated materials. For these systems, a mean-field description of their electronic properties fails, because of the strong electron-electron interactions. Their complexity leads to rich phase diagram which can easily be tuned e.g. by chemical parameters.
We have the privilege of having an artist who drew a comic book on our lab. Please have a look at the full version.
