Project Details
Projekt
Interacting spin waves in quantum antiferromagnets in two dimensions.
Subject Area
Theoretical Condensed Matter Physics
Term
since 2020
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 434439878
This project builds on the methodological progress for non-perturbative continuous similarity transformations (CSTs) in momentum space, which enables a quantitative understanding of the magnetic excitations and their dynamic correlations of the paradigmatic square-lattice Heisenberg model as well as the insights gained in the first funding period by investigating several extensions such as the XXZ-model, the Heisenberg bilayer, and the frustrated J1-J2-model. The CST maps the strongly correlated quantum many-body problem to an effective model conserving the number of dressed spin waves with strong mutual attractive interactions. Here we extend our investigation along two strands: The first strand consists in the application of the CST approach to further interesting models which are currently intensely investigated, both experimentally and theoretically. This includes the Heisenberg model on the honeycomb and the triangular lattice aiming at magnon dispersions and roton minima as well as altermagnetic systems where we are interested, besides the dispersions, in the magnon-magnon interactions as they will become relevant for computing the important transport properties subsequently. The second strand starts from the observation made in the course of the first funding period that the CST is not optimally suited to describe quantum phase transitions from the long-range ordered phase to disordered phases. Thus, we now plan to use the opposite starting point assuming that these quantum phase transitions are driven by spinon deconfinement. It is our aim to derive effective Hamiltonians for the bilayer Heisenberg model and the frustrated J1-J2-model in terms of Schwinger bosons. In case of success, this will represent a major breakthrough in the description of non-trivial quantum antiferromagnets with quantum critical points. Then, we will also consider the J-Q-model which is believed to display a deconfined quantum critical point.
DFG Programme
Research Grants
