Dynamics of Correlated Materials
Emmy Noether Group Laurenz Rettig
Dynamics of Correlated Materials
Emmy Noether Group Laurenz Rettig
Dynamics of Correlated Materials
Emmy Noether Group Laurenz Rettig

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Welcome to the Dynamics of Correlated Materials group!

    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.

     

    We currently are looking for talented postdoctoral researchers!

     

     

    News

    A quantitative comparison of time-of-flight momentum microscopes and hemispherical analyzers for time-resolved ARPES experiments
    Dec 2020
    Recent advancements in time-of-flight-based momentum microscope development have led to a growing presence of this novel detection scheme in photoemission studies, as it enables highly parallelized and simultaneous acquisition of the full 3-dimensional momentum- and energy-resolved photoelectron distribution. Combining such instruments with modern high-repetition-rate extreme ultraviolet (XUV) laser sources for ultrafast pump-probe photoemission experiments seems like an ideal match, and is followed by several groups worldwide. However, particularly important for time-resolved studies, several factors such as space-charge effects need to be considered and depend on the chosen analyzer type.
    In our study (Rev. Sci. Instr. 91, 123112 (2020)) we present a first benchmark comparison of the momentum microscope and the current standard [more...]
    An open-source, end-to-end workflow for multidimensional photoemission spectroscopy
    Dec 2020
    In our recent publication (R.P. Xian, et al., Scientific Data, 7, 442 (2020)) we present a flexible, open-source workflow for handling of single-event multidimensional photemission data. Based on a parallelized python code package, efficient data binning and conversion, as well as multidimensional coordinate transformation and calibration is provided. Our efforts aim at establishing a generic multi-purpose code platform for multidimensional photoemission spectroscopy data.
    Nonequilibrium Charge-Density-Wave Order Beyond the Thermal Limit
    Dec 2020
    Phase transitions under quasi-equilibrium conditions, e.g., induced by a slow variation of temperature, are well described by Landau theory. In contrast, the situation far from equilibrium, e.g., after ultrafast laser excitation, differs fundamentally from a thermodynamic scenario, and it remains an open question how our understanding of static phase transitions in complex matter has to be adapted to capture a dynamical, photoinduced melting and recovery of order. In particular, even the thermal critical temperature might not provide a valid description in a system exhibiting strong non-equilibrium between different degrees of freedom, such as electrons and lattice.
    In our study (arXiv:2011.03230), we investigate an ultrafast charge-density-wave-to-metal transition after optical excitation by combining state-of-the-art time-resolved electronic and structural probes. By tracking the electronic [more...]
    New group member: Jit Sarkar
    Nov 2020
    We are happy to welcome our new Postdoc Jit Sarkar to the group!
    New preprint: Ultrafast lattice of the antiferromagnet nickel oxide
    Nov 2020
    We use femtosecond electron diffraction to study ultrafast lattice dynamics in the highly correlated antiferromagnetic semiconductor NiO. Using the scattering vector (Q) dependence of Bragg diffraction, we introduce a Q-resolved effective lattice temperature and identify a nonthermal lattice state with a preferential displacement of O compared to Ni ions, which occurs within ~0.3 ps and persists for 25 ps. We associate this with transient changes to the antiferromagnetic exchange striction-induced lattice distortion, supported by the observation of a transient Q-asymmetry of Friedel pairs. Our observation highlights the role of spin-lattice coupling in routes towards ultrafast control of spin order.
    arXiv:2011.07289 (2020)