IV. Physical Institute - Ropers group
IV. Physical Institute - Ropers group

IV. Physical Institute - Ropers group

Ultrafast Dynamics and Nano-Optics

We investigate ultrafast electronic and structural dynamics in condensed matter systems. Employing laser-pump / electron-probe schemes in various configurations and at different energies, we develop and apply new experimental techniques based on imaging with ultrashort electron pulses from nanoscopic cathodes. Our activities include:

We study highly nonlinear optical processes in metallic nanostructures. Specific topics include:

Recent Highlights

Nanoscale Magnetic Imaging using High Harmonics

HHG_imaging In Science Advances (Dec. 15, 2017), we report on the first realization of magneto-optical microscopy with high-harmonic radiation. Using circularly polarized extreme-ultraviolet harmonics and x-ray magnetic circular dichroism (XMCD), we quantitatively map the magnetization in nanoscale domain patterns. A diffraction-limited spatial resolution below 50 nm is reached in full-field imaging. The work is part of a collaboration of our group with the University of Augsburg, the Technion and the I. Physical Institute.

Attosecond Pulses in the Ultrafast Transmission Electron Microscope

Attosecond_pulses_small In a recent publication, we demonstrate the generation and characterization of attosecond electron pulse trains in our Ultrafast Transmission Electron Microscope (UTEM). Along the way, we developed a scheme to reconstruct the quantum state of free-electron ensembles in terms of their density matrix. The work was published in Nature Photonics on Nov. 30, 2017.

Ultrafast Low-Energy Electron Diffraction from surfaces

TaS2_5 We have developed a new technique to study structural dynamics at surfaces, and used it to study the phase-ordering kinetics after a structural phase transition. The paper was published in Nature Physics on Nov. 6, 2017.