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MA: Fachverband Magnetismus

MA 18: Functional Antiferromagnetism I

MA 18.2: Talk

Tuesday, March 28, 2023, 15:15–15:30, HSZ 02

Magnetization dynamics in hybrid ferromagnetic / antiferromagnetic systems — •Tobias Wagner¹, Hassan Al-Hamdo², Mathias Weiler², and Olena Gomonay¹ — ¹Institut für Physik, JGU Mainz, Germany — ²Fachbereich Physik and Landesforschungszentrum OPTIMAS, RPTU in Kaiserslautern, Germany

Strong exchange coupling between Mn₂Au and thin layers of Permalloy (Ni₈₀Fe₂₀) has been shown [1]. As a consequence, the coercive field of Mn₂Au/Ni₈₀Fe₂₀ was reported to be 0.5 T, which is high compared to 0.02 T in CuMnAs/Fe [2]. Due to strong exchange coupling, the AFM Néel vector and the ferromagnetic (FM) magnetisation rotate coherently, when an external field is applied to the FM. Control of the Néel ordered state in Mn₂Au and the Ni₈₀Fe₂₀ spin dynamics has been studied by varying the Ni₈₀Fe₂₀ layer thickness [3]. Ferromagnetic resonance spectroscopy revealed two distinct frequencies for the coupled bilayer system, both of which lie above the resonance frequency of Permalloy [3]. We calculate the spectra of the magnons in the coupled FM/AFM system within micromagnetic model. Our model enables us to demonstrate how the interfacial exchange coupling enables tuning of the ferromagnetic resonance frequency by variation of the thickness of the ferromagnetic layer. We estimate the exchange coupling strength to be 5 T [3]. References: [1] Bommanaboyena, S. P. et al., Nat. Comm. 12, 6539 (2021), [2] Wadley, P. et al., Sci. Rep. 7, 11147 (2017), [3] Al-Hamdo, H. et al., unpublished.