Spin Waves Across Three-Dimensional, Close-Packed Nanoparticles
Kathryn Krycka, James Jennings Rhyne, Samuel D Oberdick, Ahmed M. Abdelgawad, Julie A. Borchers, Yumi Ijiri, Sara A. Majetich, Jeffrey W. Lynn
Inelastic neutron scattering is utilized to measure the spin waves, or magnons, which arise from inter-particle coupling between 8.4 nm ferrite nanoparticles that are self-assembled into a close-packed lattice, yet physically separated by oleic acid surfactant. The observed magnons are dispersive, respond to an applied magnetic field, and display the expected temperature-dependent Bose population factor. Moreover, the dispersion yields a non-negative energy gap only when the effective Q is reduced by the inter-particle spacing, confirming that it is an excitation between the nanoparticles ,rather than originating within individual nanoparticles. The experimental results are well explained by a limited parameter model which treats the 3D ordered, magnetic nanoparticles as dipolar-coupled superspins.
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Spin Waves Across Three-Dimensional, Close-Packed Nanoparticles, New Journal of Physics, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=924544
(Accessed November 29, 2023)