Dresden 2026 – scientific programme
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MA: Fachverband Magnetismus
MA 40: Focus Session: Chiral phonons and crystals coupled to magnetic order II
MA 40.10: Talk
Thursday, March 12, 2026, 12:30–12:45, HSZ/0002
Phonon angular momentum in ultrafast demagnetization and hybrid quasiparticles — •Markus Weißenhofer1, MS Mrudul1, Philipp Rieger1, Luca Mikadze1, Ulrich Nowak2, and Peter M. Oppeneer1 — 1Uppsala University, Uppsala, Sweden — 2Universität Konstanz, Konstanz, Germany
Transfer and manipulation of angular momentum is a key aspect in spintronics. Recently, it has been shown that angular momentum transfer between spins and phonons is possible even on ultrashort timescales [1]. To contribute to the understanding of this transfer, we investigate spin-phonon coupling using two different fully ab-initio based methods [2,4]. Using Ehrenfest nuclear dynamics simulations combined with time-dependent density functional theory, we demonstrate that after ultrafast demagnetization of FePt optical phonons carrying finite angular momentum are created [2]. In addition, we show how a novel framework [3] can be used to calculate magnon-phonon coupling parameters and hybridization from first principles, revealing the existence of chiral phonons in Fe arising from a chirality-selective magnon-phonon coupling [4].
[1] Tauchert al., Nature 602, 73 (2022); Luo et al., Science 382, 698 (2023). [2] Mrudul et al., PRB 112, L180407 (2025). [3] Mankovsky et al., PRL 129, 067202 (2022). [4] Weißenhofer et al., PRL 135, 216701 (2025).
Keywords: Spin-Phonon Coupling; Phonon Angular Momentum; Ultrafast Magnetism; Chiral Phonons; Magnon-Phonon Hybridization