MATHIEU R.

Magnetic viscosity experiments have been performed in order to investigate the magnetization reversal in Sr nanoferrite particles (nanoscale SrFe12O19) and interacting Sr/Co nanoferrite particles (SrFe12O19-CoFe2O4 nanocomposites). The magnetic viscosity S = d M ( t ) / d l n ( t ) , where M ( t ) is the magnetization as a function of time, has...

The vibrational properties of monoclinic dirutile-type CoTeO4 (space group P21/c) were investigated by means of Raman and infrared (IR) spectroscopy on stoichiometric single crystals and theoretical density-functional theory (DFT) calculations. Experimental in situ investigations under pressure and temperature variations up to 10.1 GPa and 750...

Among hard/soft nanocomposites (NCs), ferrite-based materials are potentially promising for developing exchange-coupled systems, thus leading to enhanced magnetic properties. In this regard, we investigate the role of the synthesis approach in the development of SrFe12O19/CoFe2O4 (SFO/CFO) NCs, with special focus on tuning the magnetic features...

The magnetic properties of SrFe12O19 (SFO) hard hexaferrites are governed by the complex relation to its microstructure, determining their relevance for permanent magnets´ applications. A set of SFO nanoparticles obtained by sol–gel self-combustion synthesis was selected for an in-depth structural X-Rays powder diffraction (XRPD)...

Low-cost and scalable sol–gel chemistry was employed to obtain ferroelectric-ferrimagnetic BaTiO3-CoFe2O4 nanocomposites. In a novel one-pot synthesis method, both the constituent phases of nanocomposites are formed during the same time and symbiotically participate to each other's growth. X-ray powder diffraction evidences the phase purity of...

Bi-phasic composite films are generally grown as multilayers that result in layer-by-layer morphology with each layer having a distinct chemical composition. In this work, we report an all-in-one chemical synthesis technique combined with spin-coating to prepare single-layer bi-magnetic LaFeO3 (LFO)-CoFe2O4 (CFO) composite thin films with both...

Magnetic nanocomposites (NCs) are extremely appealing for a wide range of energy-related technological applications, specifically as building blocks for next-generation permanent magnets. The design of such nanostructures requires precise chemical synthesis methods, which will permit the fine-tuning of the magnetic properties. Here we present...

In the present work, we report the preparation of multiferroic PbZr0.52Ti0.48O3 (PZT)/CoFe2O4 (CFO) nanocomposites using a new synthesis technique that can maximize the surface area of contact, and hence, the interfacial coupling between the ferroelectric (PZT) and ferrimagnetic (CFO) phases. The samples have been characterized using X-ray...

Sol-gel synthesis was used in order to obtain nanocrystallites of the SrFe12O19 (SFO) hexaferrite in an efficient and reliable way. By optimizing the initial synthetic conditions, we were able to control the size of the nanoparticles (NPs), at lower annealing temperature. The x-ray powder diffraction, transmission electron microscopy (TEM), and...

High-quality crystals of CoTeO4 were grown by application of chemical vapor transport reactions in closed silica ampoules, starting from polycrystalline material in a temperature gradient 640 °C → 580 °C with TeCl4 as transport agent. Crystal structure analysis of CoTeO4 from single crystal X-ray data revealed a dirutile-type structure with...

Over the last two decades, iron oxide based nanoparticles ferrofluids have attracted significant attention for a wide range of applications. For the successful use of these materials in biotechnology and energy, surface coating and specific functionalization is critical to achieve high dispersibility and colloidal stability of the nanoparticles...

A set of non-stoichiometric Zn-Co-ferrite nanoparticles (NPs) was prepared by thermal decomposition of metallic complexes, in the presence of oleic acid, and, after a ligand-exchange process, was coated by a hydrophilic surfactant: these NPs were used as seeds in a sol-gel self-combustion synthesis to prepare nanocomposites (NCs) with a fixed...

Magnetic nanocomposites constitute a vital class of technologically relevant materials, in particular for next-generation applications ranging from biomedicine, catalysis, and energy devices. Key to designing such materials is determining and controlling the extent of magnetic coupling in them. In this work, we show how the magnetic coupling in...

Monte Carlo simulations of the dynamic magnetic behavior of an assembly of ferromagnetic core/antiferromagnetic shell nanoparticles are reported and compared with the experimental results on a system of Co nanoparticles in Mn matrix. Memory effects on low-field zero-field-cooled magnetization curves have been investigated. Our simulations show...

Functional oxide nanocomposites, where the individual components belong to the family of strongly correlated electron oxides, are an important class of materials, with potential applications in several areas such as spintronics and energy devices. For these materials to be technologically relevant, it is essential to design low-cost and...

The non-equilibrium dynamics of the superspin glass state of a dense assembly of ~ 2 nm MnFe2O4 nanoparticles was investigated by means of magnetization, ac susceptibility and Mössbauer spectroscopy measurements and compared to the results of Monte Carlo simulations for a mesoscopic model that includes particles morphology and interparticle...