Philippe Renaud

Magnetic properties of metallic ferromagnetic nanoparticle composites

Magnetic properties of nanoparticle composites, consisting of aligned ferromagnetic nanoparticles embedded in a nonmagnetic matrix, have been determined using a model based on phenomenological approaches. Input materials parameters for this model include the saturation magnetization (Ms), the crystal anisotropy field (Hk), a damping parameter (α) that describes the magnetic losses in the particles, and the conductivity (σ) of the particles; all particles are assumed to have identical properties. Control of the physical characteristics of the composite system—such as the particle size, shape, volume fraction, and orientation—is necessary in order to achieve optimal magnetic properties (e.g., the magnetic permeability) at GHz frequencies. The degree to which the physical attributes need to be controlled has been determined by analysis of the ferromagnetic resonance (FMR) and eddy current losses at varying particle volume fractions. Composites with approximately spherical particles with radii smaller than 10...

Transport in superlattices of magnetic nanoparticles: coulomb blockade, hysteresis, and switching induced by a magnetic field.

We report on magnetotransport measurements on millimetric super-lattices of Co-Fe nanoparticles surrounded by an organic layer. At low temperature, the transition between the Coulomb blockade and the conductive regime becomes abrupt and hysteretic. The transition between both regime can be induced by a magnetic field, leading to a novel mechanism of magnetoresistance. Between 1.8 and 10 K, high-field magnetoresistance due to magnetic disorder at the surface of the particles is also observed. Below 1.8 K, this magnetoresistance abruptly collapses and a low-field magnetoresistance is observed.

Magnetoresistance and collective Coulomb blockade in superlattices of ferromagnetic CoFe nanoparticles

We report on the magnetotransport properties of chemically synthesized magnetic artificial solids consisting of millimeter-size superlattices of CoFe nanoparticles (NPs) separated by a thin organic insulating layer. Electrical measurements highlight the richness of the interaction between transport and magnetic field in three-dimensional networks of magnetic NPs, especially in the Coulomb blockade regime: (i) Resistance-temperature characteristics follow

FeCo nanoparticles from an organometallic approach: synthesis, organisation and physical properties

R={R}_{0}\text{ }\text{exp}\ensuremath{\lfloor}{({T}_{0}/T)}^{1/2}\ensuremath{\rfloor}

3000% high-field magnetoresistance in super-lattices of CoFe nanoparticles

, as generally observed in NP arrays displaying charge or structural disorder. (ii) Low-temperature current-voltage characteristics scale according to

High robustness PNP-based structure for the ESD protection of high voltage I/Os in an advanced smart power technology

I\ensuremath{\propto}{[(V\ensuremath{-}{V}_{\text{T}})/{V}_{\text{T}}]}^{\ensuremath{\zeta}}

Deep Trench NPN Transistor for Low-RON ESD Protection of High-Voltage I/Os in Advanced Smart Power Technology

with

High-field and low-field magnetoresistances of CoFe nanoparticles elaborated by organometallic chemistry

\ensuremath{\zeta}

A nanoparticule-based ferromagnetic dielectric Fe/Co composite for RF integrated inductors

ranging from 3.5 to 5.2. For a sample with a very large size distribution of NPs, a reduced exponent down to

LEGO Process for Mixed Power Applications: Fabrication at Low Cost of Localized Thick SOI Layers

\ensuremath{\zeta}=1