Speaker
Description
Magnetic nanoparticles exhibit distinctive properties governed by nanoscale effects, making them uniquely suitable for advanced technological and biomedical applications [1]. Among various designs, core/shell nanoparticles composed of spinel ferrites stand out due to their tunable magnetic responses arising from the interplay of intra- and interparticle effects [2, 3].
In this talk, we highlight specific examples of bi-magnetic core/shell nanoparticles, particularly cobalt ferrite (CoFe$_2$O$_4$, CFO) and nickel ferrite (NiFe$_2$O$_4$, NFO) in both direct (CFO/NFO) and inverse (NFO/CFO) configurations. Systematic variation of the shell thickness and particle architecture significantly affects magnetic properties (i.e., magnetic anisotropy, saturation magnetization, and magnetization dynamics). Observed effects cannot be fully described by simple additive models, pointing to a complex interaction between magnetic intraparticle (proximity effect) and interparticle interactions. Experimental insights obtained using remanent magnetization analyses ($\Delta m$-plot) and supported by Monte Carlo simulations allow us to unravel this intricate interplay, underscoring the importance of nanoscale architecture [2, 3].
Our findings emphasize the importance of nanoarchitecture in precisely tuning magnetic behaviors and suggest potential for designing materials with targeted magnetic properties. We also discuss several critical open questions: the mechanisms through which intraparticle and interparticle interactions influence each other; the distinct roles of dipolar and exchange interparticle interactions; the impact of core/shell nanoparticle architecture, including core and shell materials, layer dimensions, and shape; and how these interactions can be harnessed for designing materials with tailored magnetic properties. These examples highlight the broader possibilities awaiting discovery and optimization for applications in data storage, sensors, and biomedical devices.
Acknowledgements
This work was partially supported by the European Commission PathFinder Open programme under grant agreement no. 101046909 (REMAP, REusable MAsk Patterning) funded by the European Union. This work was partially supported byMinestro dell’Universita edella Ricerca, program ERANET Cofund ERA-MIN3, project Rendering 3D (No. JTC-2021_207).
References
[1] A. López-Ortega, et al., “Applications of exchange coupled bi-magnetic hard/soft and soft/hard magnetic core/shell nanoparticles,” Physics Reports, vol. 553. Elsevier BV, pp. 1–32, Feb. 2015. https://doi.org/10.1016/j.physrep.2014.09.007
[2] A. Omelyanchik et al., “Interplay between inter- and intraparticle interactions in bi-magnetic core/shell nanoparticles,” Nanoscale Advances, vol. 3, no. 24. Royal Society of Chemistry (RSC), pp. 6912–6924, 2021. https://doi.org/10.1039/d1na00312g
[3] A. Omelyanchik et al., “Magnetic Anisotropy and Interactions in Hard/Soft Core/Shell Nanoarchitectures: The Role of Shell Thickness,” Chemistry of Materials. American Chemical Society (ACS), Aug. 12, 2024. https://doi.org/10.1021/acs.chemmater.4c01421
