Regensburg 2025 – scientific programme

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MA: Fachverband Magnetismus

MA 7: INNOMAG e.V. Prizes 2025 (Diplom-/Master and Ph.D. Thesis)

MA 7.5: Invited Talk

Monday, March 17, 2025, 16:40–17:05, H18

Theoretical Prediction for Probing Magnon Topology — •Robin R. Neumann — Johannes Gutenberg University Mainz — Martin Luther University Halle-Wittenberg

Magnons, the bosonic quasiparticles of collective spin excitations, hold potential as information and energy carriers in spintronic devices. Although the magnonic counterpart of the electronic quantum Hall states was predicted over a decade ago [1, 2], experimental evidence remains absent because established methods fail to probe them [3].

In my thesis I have studied the signatures of topological magnons in transport and spectroscopic observables. While I demonstrated that the thermal Hall effect can be sensitive to topological phase transitions in the magnon band structure [4], magnon-phonon hybridization may obscure their contributions [5]. I present a specific proposal for using electrical probes to detect topological magnons [6]. Despite their charge neutrality, magnetoelectric effects grant magnons an electrical dipole moment. Consequently, edge magnons give rise to an electric polarization at the edges driven by thermal spin fluctuations. Furthermore, magnons are predicted to interact with alternating electric fields, opening up the possibility of resonantly exciting topological magnons. The resulting absorption spectrum encodes footprints of topological magnons that might assist in their detection.

[1] Zhang et al., PRB 87, 144101 (2013), [2] Shindou et al., PRB 87, 174427 (2013), [3] Malz et al., Nat. Commun. 10, 3937 (2019), [4] RRN et al., PRL 128, 117201 (2022), [5] RRN et al., PRB 108, L140402 (2023), [6] RRN et al., PRB 109, L180412 (2024)

Keywords: Magnons; Topology; Chiral edge states; Thermal Hall effect; THz spectroscopy