Lecture image placeholder

Premium content

Access to this content requires a subscription. You must be a premium user to view this content.

Monthly subscription - $9.99Pay per view - $4.99Access through your institutionLogin with Underline account
Need help?
Contact us
Lecture placeholder background
VIDEO DOI: https://doi.org/10.48448/d3q4-0716

technical paper

MMM 2022

November 07, 2022

Minneapolis, United States

Interparticle magnetic correlations and dynamics of fluctuations in assemblies of Fe3O4 nanoparticles

Magnetic nanoparticles (NPs) provide an ideal support for developing a wide range of nanotechnologies and biomedical applications, such as drug-delivery, gene delivery, hyperthermia, or contrast agents for MRI.1 Magnetite (Fe3O4 ) NPs are good candidates for these applications due to their non-toxicity and long-life in the bloodstream. To optimize these applications, it is crucial to well control the magnetic response of individual NP when manipulating a collection of them via a magnetic field. In particular, it is useful to identify any interparticle magnetic correlations that may cause the magnetic response to deviate from superparamagnetism, induce superferromagnetism and magnetic hysteresis, and affect the dynamics of fluctuations. To that end, we have studied the magnetic response of 5 – 100 nm Fe3O4 NPs and its dependence on NP size, using magnetometry 2 and spin muon resonance 3. However, this information remains macroscopic or spatially averaged. Here we show how nanoscale spatial information on inter-particle magnetic correlations can be obtained via xray resonant magnetic scattering (XRMS) 4 as illustrated in Figure 1. By tuning the energy of the x-rays to resonant edges of Fe and comparing opposite polarization helicities, we have extracted information about the local inter-particle magnetic orders within NP assemblies of various sizes.5 We fitted the XRMS data using a model based on chains of NPs.6 The data fitting shows ferromagnetic ordering when an external magnetic field is applied, and the emergence of antiferromagnetic ordering, competing with magnetic randomness, when the field is brought back near the coercive point (zero net magnetization). We studied how these correlations depend on particle size and found an enhancement of magnetic couplings and antiferromagnetic orders for bigger particles. 7 Additionally we will show preliminary studies of the dynamics of magnetic fluctuations via x-ray photon correlation spectroscopy (XPCS).
1. Frey et al., Chem. Soc. Rev. 2009, 38, 2532-2542 (2009)
2. Klomp et al., IEEE Trans. Mag. 56, 2300109 (2020)
3. Frandsen et al., Phys. Rev. Matter 5, 054411 (2021)
4. Kortright et al., Phys. Rev. B 71, 012402 (2005)
5. Chesnel et al., Magnetochemistry 4, 42-58 (2018)
6. Rackham et al., AIP Advances 9, 035033 (2019)
7. Rackham et al., to be submitted (2022)

Figure 1: Layout of the x-ray resonant magnetic scattering (XRMS) measurement of a nanoparticle assembly.


Transcript English (automatic)

Next from MMM 2022

Harnessing the spin and orbital dynamics of iron based 2D van der Waals ferromagnets
technical paper

Harnessing the spin and orbital dynamics of iron based 2D van der Waals ferromagnets

MMM 2022

Tom Saunderson and 20 other authors

07 November 2022

Stay up to date with the latest Underline news!

Select topic of interest (you can select more than one)


  • All Lectures
  • For Librarians
  • Resource Center
  • Free Trial
Underline Science, Inc.
1216 Broadway, 2nd Floor, New York, NY 10001, USA

© 2023 Underline - All rights reserved