Berlin 2024 – scientific programme

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MA: Fachverband Magnetismus

MA 29: Spin-Dependent Phenomena in 2 D

MA 29.3: Talk

Wednesday, March 20, 2024, 15:30–15:45, EB 202

Topological magnon gap engineering in layered van der Waals ferromagnet CrI3 — •Verena Brehm¹, Pawel Sobieszczyk², Jostein Kløgetvedt¹, Richard F. L. Evans³, Elton J. G. Santos⁴, and Alireza Qaiumzadeh¹ — ¹NTNU Trondhem, Norway — ²Polish Academy of Sciences Krakow, Poland — ³University of York, United Kingdom — ⁴University of Edinburgh, Untied Kingdom

We investigate the angular magnetic field dependence of the topological magnon gap at the K-points of the ferromagnetic van der Waals insulator CrI3, by examining two gap-opening terms: the Dzyaloshinski-Moriya and Kitaev interaction. Using stochastic atomistic spin dynamics simulations and linear spin wave theory, we compare the impact of the two spin interactions on the magnon spectra in a single layer. We observe three distinct magnetic field dependencies between these two topological magnon gap opening mechanisms that may distinguish the origin of the topological magnon gap. First, we demonstrate that the Kitaev-induced magnon gap is influenced by both the direction and amplitude of the applied magnetic field, while the DM-induced gap is solely affected by the magnetic field direction. Second, our findings reveal that the position of the Dirac cones within the Kitaev-induced magnon gap shifts dependent on the magnetic field direction, whereas they remain unaffected in the DM-induced gap scenario. Third, we find a direct-indirect magnon band-gap transition in the Kitaev model by varying the applied magnetic field.

Keywords: topological magnon gap; van der Waals materials; Kitaev and Dzyaloshinski-Moriya interaction; atomistic spin simulations