Simultaneous Individual and Dipolar Collective Properties in Binary Assemblies of Magnetic Nanoparticles
Artikel i vetenskaplig tidskrift, 2020
Applications based on aggregates of magnetic nanoparticles are becoming increasingly widespread, ranging from hyperthermia to magnetic recording. However, although some uses require collective behavior, others need a more individual-like response, the conditions leading to either of these behaviors are still poorly understood. Here, we use nanoscale-uniform binary random dense mixtures with different proportions of oxide magnetic nanoparticles with low/high anisotropy as a valuable tool to explore the crossover from individual to collective behavior. Two different anisotropy scenarios have been studied in two series of binary compacts: M1, comprising maghemite (gamma-Fe2O3) nanoparticles of different sizes (9.0 nm/11.5 nm) with barely a factor of 2 between their anisotropy energies, and M2, mixing equally sized pure maghemite (low-anisotropy) and Co-doped maghemite (high-anisotropy) nanoparticles with a large difference in anisotropy energy (ratio > 8). Interestingly, while the M1 series exhibits collective behavior typical of strongly coupled dipolar systems, the M2 series presents a more complex scenario where different magnetic properties resemble either "individual-like" or "collective", crucially emphasizing that the collective character must be ascribed to specific properties and not to the system as a whole. The strong differences between the two series offer new insight (systematically ratified by simulations) into the subtle interplay between dipolar interactions, local anisotropy and sample heterogeneity to determine the behavior of dense assemblies of magnetic nanoparticles.
DYNAMICS
MODEL
SUPERPARAMAGNETISM
SPIN DISORDER
NANOCRYSTAL SUPERLATTICES
COFE2O4
REMANENCE
MAGNETORESISTANCE
RANDOM ANISOTROPY
CHARGE-DISTRIBUTION
Författare
Elena H. Sanchez
Universidad de Castilla, La Mancha
Marianna Vasilakaki
Fundacio Institut Catala de Nanociencia i Nanotecnologia (ICN2)
Su Seong Lee
Inst Bioengn & Nanotechnol
Peter S. Normile
Universidad de Castilla, La Mancha
Giuseppe Muscas
Uppsala universitet
Universita degli Studi di Cagliari
Massimiliano Murgia
Universidad de Castilla, La Mancha
Universita degli Studi di Cagliari
Mikael Andersson
Uppsala universitet
Chalmers, Kemi och kemiteknik, Energi och material
Gurvinder Singh
The University of Sydney
Roland Mathieu
Uppsala universitet
Per Nordblad
Uppsala universitet
Pier Carlo Ricci
Universita degli Studi di Cagliari
Davide Peddis
Università degli Studi di Genova
Consiglio Nazionale delle Ricerche (CNR)
Kalliopi N. Trohidou
Fundacio Institut Catala de Nanociencia i Nanotecnologia (ICN2)
Josep Nogues
Institucio Catalana de Recerca i Estudis Avancats
Consejo Superior de Investigaciones Científicas (CSIC)
Jose A. De Toro
Universidad de Castilla, La Mancha
Chemistry of Materials
0897-4756 (ISSN) 1520-5002 (eISSN)
Vol. 32 3 969-981Ämneskategorier
Oorganisk kemi
Fysikalisk kemi
Den kondenserade materiens fysik
DOI
10.1021/acs.chemmater.9b03268