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, Oorganisk miljökemi 2

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 3 969-981

Ämneskategorier

Oorganisk kemi

Fysikalisk kemi

Den kondenserade materiens fysik

DOI

10.1021/acs.chemmater.9b03268

Mer information

Senast uppdaterat

2020-05-25