A5064112926- Magnetic properties of thin films
- Magnetic Properties and Synthesis of Ferrites
- Characterization and Applications of Magnetic Nanoparticles
- Theoretical and Computational Physics
- Iron oxide chemistry and applications
- Magnetic Properties and Applications
- Advanced Condensed Matter Physics
- Magnetic Properties of Alloys
- Multiferroics and related materials
- Physics of Superconductivity and Magnetism
- Solar-Powered Water Purification Methods
- Supercapacitor Materials and Fabrication
- Solar Thermal and Photovoltaic Systems
- Electrostatics and Colloid Interactions
- nanoparticles nucleation surface interactions
- Nanoparticle-Based Drug Delivery
- Geomagnetism and Paleomagnetism Studies
- Gas Sensing Nanomaterials and Sensors
- Metallic Glasses and Amorphous Alloys
- Advancements in Battery Materials
- Fractional Differential Equations Solutions
- ZnO doping and properties
- Advanced Thermoelectric Materials and Devices
- Transition Metal Oxide Nanomaterials
- Quantum, superfluid, helium dynamics
National Centre of Scientific Research "Demokritos"
2015-2024
Centre de Nanosciences et de Nanotechnologies
2015
KTH Royal Institute of Technology
2008
Universitat Autònoma de Barcelona
2008
Instituto de Ciencia de Materiales de Sevilla
2008
The magnetic properties of maghemite (γ-Fe2O3) cubic and spherical nanoparticles similar sizes have been experimentally theoretically studied. blocking temperature, TB, the depends on their shape, with ones exhibiting larger TB. Other low temperature such as saturation magnetization, coercivity, loop shift or spin canting are rather similar. experimental effective anisotropy Monte Carlo simulations indicate that different random surface two morphologies combined magnetocrystalline γ-Fe2O3 is...
Magnetization and AC susceptibility measurements have been performed on ∼3 nm NiO nanoparticles in powder form. The results indicate that the structure of particles can be considered as consisting an antiferromagnetically ordered core, with uncompensated magnetic moment, a magnetically disordered surface shell. core moments block progressively decreasing temperature, according to distribution their anisotropy energy barriers, shown by broad maximum low field zero-field-cooled magnetization...
We have used the Monte Carlo simulation technique to investigate effect of a ferrimagnetic disordered shell on hysteresis behavior composite magnetic nanoparticles with ferromagnetic core/ferrimagnetic morphology. examined cooling field $({H}_{\text{cool}})$ dependence exchange bias $({H}_{\text{ex}})$, coercive $({H}_{c})$, and remanent magnetization $({M}_{r})$ we find that an increase in ${H}_{\text{cool}}$ results initially ${H}_{\text{ex}}$, ${H}_{c}$, ${M}_{r}$, while further causes...
The intimate relationship between stoichiometry and physicochemical properties in transition-metal oxides makes them appealing as tunable materials. These features become exacerbated when dealing with nanostructures. However, due to the complexity of nanoscale materials, establishing a distinct structure-morphology functionalities is often complicated. In this regard, FexO/Fe3O4 system largely unexplained broad dispersion magnetic has been observed. Here we show, thanks comprehensive...
Inverted soft/hard, in contrast to conventional hard/soft, bi-magnetic core/shell nanoparticles of MnxFe3−xO4/FexMn3−xO4 with two different core sizes (7.5 and 11.5 nm) fixed shell thickness (∼0.6 have been synthesized. The structural characterization suggests that the particles an interface a graded composition. magnetic confirms inverted soft/hard structure evidences strong exchange coupling between shell. Moreover, larger soft exhibit smaller coercivities loop shifts, but blocking...
Abstract Bi-magnetic core/shell nanoparticles are gaining increasing interest due to their foreseen applications. Inverse antiferromagnetic(AFM)/ferrimagnetic(FiM) particularly appealing since they may overcome some of the limitations conventional FiM/AFM systems. However, virtually no simulations exist on this type morphology. Here we present systematic Metropolis Monte Carlo exchange bias properties such nanoparticles. The coercivity, H C and loop shift, ex , a non-monotonic dependence...
Remanence magnetization plots (e.g., Henkel or δM plots) have been extensively used as a straightforward way to determine the presence and intensity of dipolar exchange interactions in assemblies magnetic nanoparticles single domain grains. Their evaluation is particularly important functional materials whose performance strongly affected by interparticle interactions, such patterned recording media nanostructured permanent magnets, well applications hyperthermia resonance imaging. Here, we...
Dynamical susceptibility and Monte Carlo simulations unravel the spin-glass dynamics due to assembly of colloidal nanoparticles in clusters with increased volume fraction.
Monte Carlo simulations of the dynamic magnetic behavior an assembly ferromagnetic core/antiferromagnetic shell nanoparticles are reported and compared with experimental results on a system Co in Mn matrix. Memory effects low-field zero-field-cooled magnetization curves have been investigated. Our show that memory increase concentration both interface exchange coupling dipolar interparticle interactions contribute to observed behavior. In particular interaction provides additive source for...
Optimizing the heating properties of magnetic nanoparticles by their core/shell morphology, size and shape, a theoretical study.
Optimising the magnetic properties of CoFe<sub>2</sub>O<sub>4</sub> nanoparticles by selecting appropriate coating in a ligand exchange process.
Applications based on aggregates of magnetic nanoparticles are becoming increasingly widespread, ranging from hyperthermia to recording. However, although some uses require collective behavior, others need a more individual-like response, the conditions leading either these behaviors still poorly understood. Here, we use nanoscale-uniform binary random dense mixtures with different proportions oxide low/high anisotropy as valuable tool explore crossover individual behavior. Two scenarios...
Abstract Dense systems of magnetic nanoparticles may exhibit dipolar collective behavior. However, two fundamental questions remain unsolved: i) whether the transition temperature be affected by particle anisotropy or it is essentially determined intensity interparticle interactions, and ii) what minimum ratio dipole–dipole interaction ( E dd ) to nanoparticle K ef V , anisotropy⋅volume) energies necessary crossover from individual A series assemblies with similarly intense interactions but...
This paper shed lights on the interplay among intra- and inter-particle interactions in different hard/soft bi-magnetic core/shell nanoarchitecture.
The magnetism of a dense assembly ultrasmall ferrimagnetic nanoparticles exhibits unique features due to the combination intraparticle and strong interparticle interactions. To model such system we need account for internal particle structure short- long-range We have developed mesoscopic that includes three spins (two surface one core) description each nanoparticle, dipolar interactions exchange in contact. temperature dependence observed bias effect, coupling at interface between...
Chromium nanoparticles are formed using superfluid helium droplets as the nanoreactors, which strongly ferromagnetic. The transition from antiferromagentism to ferromagnetism is attributed atomic-scale disorder in chromium nanoparticles, leading abundant unbalanced surface spins. Theoretical modeling confirms a frustrated aggregation process due antiferromagnetic nature of chromium. First postulated by Louis Néel 1936,1 ordering elemental was confirmed 1953 neutron diffraction.2 antiparallel...
The structural and magnetic properties of 1.8 nm Co particles dispersed in a Mn matrix by co-depositing pre-formed mass-selected clusters with an atomic vapour onto common substrate have been studied using EXAFS (extended x-ray absorption fine structure), XMCD (x-ray circular dichroism), magnetometry, theoretical modelling. At low volume fraction (5%) Co@Mn shows significant degree alloying the well-defined originally deposited become centres high concentration CoMn alloy that evolves from...
In contrast to bulk materials, nanoscale crystal growth is critically influenced by size- and shape-dependent properties. However, it challenging decipher how stoichiometry, in the realm of mixed-valence elements, can act control physical properties, especially when complex bonding implicated short long-range ordering structural defects. Here, solution-grown iron-oxide nanocrystals (NCs) pilot wustite system are found convert into iron-deficient rock-salt ferro-spinel sub-domains, but attain...
In this work, the influence of shell thickness on magnetic behavior hard cobalt ferrite (CoFe2O4) nanoparticles coated with one or more layers magnetically soft nickel (NiFe2O4) was investigated. The materials were chosen as model and magnetics due to their significant difference in anisotropy constant, which spans 2 orders magnitude. obtained nanoarchitectures are compositionally graded single crystals, i.e., they comprise a crystallographic coherence core no visible core–shell interface at...