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Separating spin dynamics modes in iron oxide nanoparticles

M. Zobel1,2,*, M. Appel3, S. L. J. Thomä4, M. Plekhanov2, and A. Magerl1,5

  • *Contact author: m.zobel@fz-juelich.de, she/her
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Phys. Rev. B 111, L060406 – Published 11 February, 2025

DOI: https://doi.org/10.1103/PhysRevB.111.L060406

Abstract

The different modes of the spin dynamics in ferrimagnetic magnetite iron oxide nanoparticles (Fe3O4) have been addressed by µeV neutron spectroscopy for particles with a diameter of 75 ± 18 Å. In an approach building on intensity considerations over a wide range of wave vectors Q in combination with diffusion dynamics, we identify three magnetic modes prevailing in distinct Q regimes up to 1.7 Å−1: (i) Evaluating the structure factor of quasielastic magnetic intensity enables to identify uniquely longitudinal superparamagnetic spin fluctuations in the small Q regime <0.5Å−1, (ii) individual spin relaxation with quasielastic intensity albeit of low intensity is present in two Q ranges of 0.5 Å−1<Q<1.0Å−1 and 1.5 Å−1<Q<1.7Å−1, and (iii) a surprisingly low-energy inelastic spin excitation of 23.2 µeV in magnetite IONPs is found at 150 K in the magnetic Bragg region between 1.1 Å−1<Q<1.4Å−1. Its temperature dependence suggests a collapse of the coherent transverse magnetic fluctuations and a transition into a generalized diffusive mode at about 500 K.

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References (17)

  1. S. Bader, Colloquium: Opportunities in nanomagnetism, Rev. Mod. Phys. 78, 1 (2006).
  2. I. Hilger and W. A. Kaiser, Iron oxide-based nanostructures for MRI and magnetic hyperthermia, Nanomedicine 7, 1443 (2012).
  3. S. Mørup and B. R. Hansen, Uniform magnetic excitations in nanoparticles, Phys. Rev. B 72, 024418 (2005).
  4. M. F. Hansen, F. Bødker, S. Mørup, K. Lefmann, K. N. Clausen, and P. A. Lindgård, Dynamics of magnetic nanoparticles studied by neutron scattering, Phys. Rev. Lett. 79, 4910 (1997).
  5. S. Disch, R. P. Hermann, E. Wetterskog, A. A. Podlesnyak, K. An, T. Hyeon, G. Salazar-Alvarez, L. Bergstrom, and Th. Bruckel, Spin excitations in cubic maghemite nanoparticles studied by time-of-flight neutron spectroscopy, Phys. Rev. B 89, 064402 (2014).
  6. M. Eckardt, S. L. J. Thomä, M. Dulle, G. Hörner, B. Weber, S. Förster, and M. Zobel, Long-term colloidally stable aqueous dispersions of ≤5 nm spinel ferrite nanoparticles, ChemistryOpen 9, 1214 (2020).
  7. S. L. J. Thomä, S. W. Krauss, M. Eckardt, P. Chater, and M. Zobel, Atomic insight into hydration shells around facetted nanoparticles, Nat. Commun. 10, 995 (2019).
  8. M. Appel, B. Frick, and A. Magerl, First Results with the Neutron Backscattering and TOF Spectrometer Option BATS on IN16B, Physica B Condens. Matter 562, 6 (2019).
  9. M. S. Plekhanov, S. L. J. Thomä, A. Magerl, M. Appel, and M. Zobel, Quasi-elastic neutron scattering of citrate-capped iron oxide nanoparticles: Distinguishing between ligand, water, and magnetic dynamics, J. Phys. Chem. C 128, 11661 (2024).
  10. M. Hennion, C. Bellouard, I. Mirebeau, J. L. Dormann, and M. Nogues, Dual spin dynamics of small Fe particles, Europhys. Lett. 25, 43 (1994).
  11. M. Mikhaylova, D. K. Kim, N. Bobrysheva, M. Osmolowsky, V. Semenov, T. Tsakalakos, and M. Muhammed, Superparamagnetism of magnetite nanoparticles: Dependence on surface modification, Langmuir 20, 2472 (2004).
  12. S. Disch, E. Wetterskog, R. P. Hermann, A. Wiedenmann, U. Vainio, G. Salazar-Alvarez, L. Bergström, and Th. Brückel, Quantitative spatial magnetization distribution in iron oxide nanocubes and nanospheres by polarized small-angle neutron scattering, New J. Phys. 14, 13025 (2012).
  13. D. Zákutná, N. Rouzbeh, D. Nižňanský, J. Duchoň, A. Qdemat, E. Kentzinger, and D. Honecker, Magnetic coupling in cobalt-doped iron oxide core–shell nanoparticles: Exchange pinning through epitaxial alignment, Chem. Mater. 35, 2302 (2023).
  14. For example, see P.-A. Lindgård, in Spin Waves and Magnetic Excitations 1, edited by A. S. Borovik-Romanov and S. K. Sinha (Elsevier, New York, 1988), p. 287.
  15. K. Lefmann, F. Bødker, S. N. Klausen, M. F. Hansen, K. N. Clausen, P.-A. Lindgård, and S. Mørup, A neutron scattering study of spin precession in ferrimagnetic maghemite nanoparticles, Europhys. Lett. 54, 526 (2001).
  16. W. F. Brown, Jr., Thermal fluctuations of a single-domain particle, Phys. Rev. 130, 1677 (1963).
  17. https://doi.ill.fr/10.5291/ILL-DATA.INTER-528.

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Phys. Rev. B 111, L060406– Published 11 February, 2025
  • Received 26 July 2024
  • Accepted 3 February 2025
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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