Welcome to the Dynamics of Correlated Materials group!
XUV generation
High-repetition rate OPCPA
Bond breaking and formation during and ultrafast phase transition
Fermi surface dynamics covering multiple Brillouin zones
Ultrafast dynamics of antiferromagnetic spin arrangements
We are an experimental research group focusing on the investigation of ultrafast processes in strongly correlated materials. Our goal is the understanding of the fundamental interactions at play on the microscopic level in such materials, leading to complex behavior. We develop and employ complementary ultrafast techniques such as time- and angle-resolved photoelectron spectroscopy (trARPES) and time-resolved diffraction techniques to study those elementary interaction processes and couplings across ultrafast phase transitions.
News
New group member: Caio Silva
Jan 2020
We are happy to welcome our new Postdoc Caio Silva to the group!
First time- and momentum-resolved photoemission studies using time-of-flight momentum microscopy at a free-electron laser.
Jan 2020
The free-electron laser FLASH at DESY in Hamburg delivers femtosecond soft-x-ray pulses which allow unique applications in the field of time-resolved photoelectron spectroscopy. We participated in a larger consortium establishing time-resolved momentum microscopy with such 4th generation photon sources. Our paper describing this technical development can be found here: D. Kutnyakhov et al., First time- and momentum-resolved photoemission studies using time-of-flight momentum microscopy at a free-electron laser. Rev. Sci. Instr. 91, 013109 (2020)
New website released!
May 2019
Our website was migrated to the new server and a new design.
Highlight: Ultrafast Dynamics of Atomic Motion Viewed by the Electrons in Solids
Nov 2018
Capturing the motions of atoms in a so-called “molecular movie” is generally thought of as the Holy Grail for understanding chemical transformations or structural phase transitions in solids. However, atomic motion is not the whole story, as the forces driving these motions arise from details of the electronic structure and a gradient across a free energy landscape. Therefore, to obtain a complete picture of the processes driving structural changes, it is necessary to observe the dynamics of the electronic structure and track the temporal evolution of electronic states and their populations. By using femtosecond lasers to perform time- and angle-resolved photoemission spectroscopy, the changes of the electronic structure during the phase transition in indium nanowires on a silicon surface could be closely monitored, allowing a detailed reaction pathway to be extracted. This information combined with simulations of the electronic [more...]
New paper published: Ultrafast spin density wave transition in Chromium governed by thermalized electron gas
Dec 2016
Time-resolved ARPES allows direct access to the electronic signatures of broken symmetry phases, as well as their femtosecond dynamics. By measuring the spin density wave (SDW) transition in thin films of Cr, we study the dynamics of a phase transition in which the role of the lattice is minimized, in contrast to conventional charge density wave or superconducting materials. This allows for a more stringent test of the role played by the electronic temperature in driving materials from one phase to another under non-equilibrium conditions. By comparison with a mean field model we are able to quantitatively extract the evolution of the SDW order parameter through the ultrafast phase transition, and show that it is governed by the transient temperature of the thermalized electron gas. This shows that for phases governed by the temperature of a single sub-system (e.g. electronic, phononic) concepts from thermodynamic equilibrium are still applicable. [more...]
