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


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.





    Observation of an excitonic Mott transition through ultrafast core-cum-conduction photoemission spectroscopy
    Apr 2020
    Optoelectronic applications root on excited electronic states. In semiconductors, there are two types of excited states: many-body states like bound electron-hole states, so-called excitons, and simpler quasi-particle states, typically referred to as quasi-free carriers (QFCs). In general, both types coexist in a dynamical interplay of exciton and QFC populations.
    Using the free-electron laser Flash at Desy in Hamburg in conjunction with a time-of-fligh momentum microscope, we were able to track the time-dependent electronic structure of the layered semiconductor WSe2 on an ultrafast timescale. Our findings reported here (arXiv:2003.12925) demonstrate a novel, at first glance counter-intuitive approach for accessing exciton and QFC dynamics on ultrafast time scales: the photoemission lineshapes of core levels, i.e. states deep below the frontier orbitals, turn out to be sensitive probes [more...]
    Ultrafast Light-Induced Lifshitz Transition
    Mar 2020
    In crystalline solids, electrons fill quantum-mechanically allowed states from the lowest possible energy upwards, a consequence of the Pauli exclusion principle. The energy of the highest occupied state is known as the Fermi energy. Because electrons within solids have well-defined three-dimensional momenta, one can plot components of these momenta against each other, for electron lying at the Fermi energy, leading to characteristic and often beautiful shape, bounded by a so-called Fermi surface.
    The Fermi surface is “the stage where the drama of the life of the electron is played out,” wrote famous physicists Lifshitz and Kaganov, in 1980. Indeed, the shape of the Fermi surface governs most of the properties of metals and strongly correlated many-body systems. Equilibrium tuning of macroscopic parameters such as temperature, pressure, strain or doping has recently been established as robust tools to modify the Fermi surface [more...]
    Mar 2020
    Due to the worldwide corona-pandemic, wer are currently working in home office. The best way to reach us is via email.
    We wish everybody to stay healthy and get through this difficult time!
    Deterministic control of an antiferromagnetic spin arrangement using ultrafast optical excitation
    Feb 2020
    A central prospect of antiferromagnetic spintronics is to exploit magnetic properties that are unavailable with ferromagnets. However, this poses the challenge of accessing such properties for readout and control. To this end, light-induced manipulation of the transient ground state, e.g. by changing the magnetic anisotropy potential, opens promising pathways towards ultrafast deterministic control of antiferromagnetism. Here, we use this approach to trigger a coherent rotation of the entire long-range antiferromagnetic spin arrangement about a crystalline axis in GdRh2Si2 and demonstrate deterministic control of this rotation upon ultrafast optical excitation. Our observations can be explained by a displacive excitation of the Gd spins′ local anisotropy potential by the optical excitation, allowing for a full description of this transient magnetic anisotropy potential.
    New group member: Caio Silva
    Jan 2020
    We are happy to welcome our new Postdoc Caio Silva to the group!