Dresden 2020 – scientific programme
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MA: Fachverband Magnetismus
MA 29: Focus Session: Magnon Polarons – Magnon-Phonon Coupling and Spin Transport (joint session MA/HL)
MA 29.8: Talk
Wednesday, March 18, 2020, 12:45–13:00, HSZ 04
Topological Magnon-Phonon Hybrid Excitations in Two-Dimensional Ferromagnets with Tunable Chern Numbers — •Gyungchoon Go1, Se Kwon Kim2, and Kyung-Jin Lee1,3 — 1Department of Materials Science and Engineering, Korea University, Seoul 02841, Korea — 2Department of Physics and Astronomy, University of Missouri, Columbia, Missouri 65211, USA — 3KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea
We theoretically investigate magnon-phonon hybrid excitations in two-dimensional ferromagnets. The bulk bands of hybrid excitations, which are referred to as magnon polarons, are analytically shown to be topologically nontrivial, possessing finite Chern numbers. We also show that the Chern numbers of magnon-polaron bands and the number of band-crossing lines can be manipulated by an effective magnetic field. For experiments, we propose to use the thermal Hall conductivity as a probe of the finite Berry curvatures of magnon-polarons. Our results show that a simple ferromagnet on a square lattice supports topologically nontrivial magnon polarons, generalizing topological excitations in conventional magnetic systems.