Regensburg 2025 – scientific programme

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MA: Fachverband Magnetismus

MA 43: Skyrmions III / Non-Skyrmionic Magnetic Textures II

MA 43.7: Talk

Friday, March 21, 2025, 11:00–11:15, H16

Field-induced Reversal of Magnetic Anisotropy in Skyrmion Hosts — •Hans-Albrecht Krug von Nidda, Bertalan Szigeti, Mamoun Hemmida, Dieter Ehlers, and István Kézsmárki — Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, D-86135 Augsburg, Germany

Skyrmions show up in non-centrosymmetric magnets due to the complex interplay of anisotropic Dzyaloshinskii-Moriya interaction, uniaxial magnetic anisotropy, and magnetic dipolar interactions. A magnet is commonly classified as either easy-axis or easy-plane, when the magnetic anisotropy forces the magnetization to align parallel or perpendicular to the high-symmetry axis, respectively. We show that this simple classification fails for systems with competing anisotropy terms. Our multi-frequency electron spin resonance spectroscopy study on the skyrmion hosts GaMo4S8 and GaV4Se8 reveals counteracting exchange and g-factor anisotropies. Consequently, the total aniotropy changes sign in moderate magnetic fields: GaMo4S8 turns from an easy- to a hard-axis magnet, while GaV4Se8 does the opposite. These findings underscore the significance of precisely quantifying all anisotropy components, because a single effective value, when encompassing conflicting terms, proves to be insufficient for an accurate description of magnetic states.

Keywords: magnetic anisotropy; ferromagnetic resonance; lacunar spinels