Regensburg 2025 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 48: Ultrafast Magnetization Effects II
MA 48.2: Vortrag
Freitag, 21. März 2025, 11:30–11:45, H20
Dynamical renormalization of the magnetic excitation spectrum via high-momentum nonlinear magnonics — •Julian Bär1, Lennart Feuerer1, Alfred Leitenstorfer1, Dominik Juraschek2, and Davide Bossini1 — 1Department of Physics and Center for Applied Photonics, University of Konstanz, D-78464 Konstanz, Germany — 2Department of Applied Physics and Science Education, Eindhoven University of Technology, Eindhoven, Netherlands
Manipulating the macroscopic properties of solids with light is a key challenge in condensed matter physics. While resonantly driving low-momentum collective excitations has led to nonlinear lattice and spin dynamics [1,2], controlling magnon spectra in terms of amplitude and frequency remains unexplored. In my talk I will discuss the resonant excitation of pairs of high-momentum magnons in Hematite (α-Fe2O3). By exciting hematite in its weak-ferromagnetic phase, our approach results in a direct coupling between high- and low-momentum magnons. In particular, the spectrum of the latter is modified. This astonishing effect is explained with a resonant light-scattering mechanism that couples high- and low-momentum eigenmodes across momentum space [3]. As hematite undergoes a phase transition at 260 K to a collinear antiferromagnetic state, we have developed a cryogenic pump-probe setup. Preliminary results reveal behaviour distinct from that observed in the weak ferromagnetic phase. [1] A. S. Disa et al., Nat Phys 17, 1087-1092 (2021). [2] Z. Zhang et al., Nat Phys., 1-6 (2024). [3] C. Schoenfeld et al., arXiv:2310.19667 (2024)
Keywords: mid-infrared; Nonlinear Magnonics; Hematite; Ultrafast Magnetism; Pump-Probe Experiments