Abstract
Six nanometer sized iron-oxide nanoparticles capped with an organic surfactant and/or silica shell of various thicknesses have been synthesized by a microemulsion method to enable controllable contributions of interparticle magnetic dipole interaction via tunable interparticle distances. Bare particles with direct surface contact were used as a reference to distinguish between interparticle interaction and surface effects by use of Mössbauer spectroscopy. Superparamagnetic relaxation behaviour was analyzed by SQUID-magnetometry techniques, showing a decrease of the blocking temperature with decreasing interparticle interaction energies kBT0 obtained by AC susceptibility. A many-state relaxation model enabled us to describe experimental Mössbauer spectra, leading to an effective anisotropy constant Keff ≈ 45 kJm−3 in case of weakly interacting particles, consistent with results from ferromagnetic resonance. Our unique multi-technique approach, spanning a huge regime of characteristic time windows from about 10 s to 5 ns, provides a concise picture of the correlation of superparamagnetic relaxation with interparticle magnetic dipole interaction.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
