Claudio Serpico - Research Interests
Current and past research interests and activities
- Micromagnetics
- Computational and analytical investigations of nonlinear magnetization dynamics in
magnetic systems of nanometric or micrometric dimensions.
I have carried out investigations of magnetization dynamics in nano-scale and micro-scale systems in different excitation conditions: pulsed, microwave and
constant applied magnetic fields. Within the time and spatial scales of interest,
these magnetic systems can be modeled by using the Micromagnetic continuum theory
and its dynamical generalization: the Landau-Lifshitz equation. The problems treated
are particularly relevant to the area of magnetic recording and magnetic storage
technologies.
Cooperations: University of Maryland, College Park MD, USA;
IEN Galileo Ferraris Torino, Italy; TUW Vienna.
- Computational and analytical investigations of nonlinear magnetization dynamics in
nanomagnets traversed by spin-polarized electric current. In these magnetic systems,
magnetization dynamics is driven by the Spin-Torque effects due to the transfer of
spin angular momentum. These investigations are relevant to spintronics and spintorque
devices.
Cooperations: University of Maryland,College Park MD, USA; IEN Galileo Ferraris Torino, Italy;
TUW Vienna
- Hysteresis Modeling, Magnetic Field Diffusion and Eddy Currents in Ferromagnetic Materials
- Investigations on accurate phenomenological modeling of Hysteresis in Ferromagnetic
Hysteresis in macroscopic magnetic bodies.
By using an approach inspired by the classical Preisach model,
the constitutive relation between magnetization and applied field
is represented as the superposition of a set of elementary hysteresis
operators which are instrumental to describe multiple metastable states.
This superposition is weighted by appropriate distribution functions
which are to be identified from set of hysteresis measurements.
Cooperations: University of Maryland,College Park MD, USA; IEN Galileo Ferraris Torino, Italy;
Cairo University, Egypt
- Diffusion of magnetic field and eddy currents in ferromagnetic conductors has been studied
by numerically computing the coupling between the constitutive
relation with hysteresis and quasi-stationary Maxwell Equations.
Cooperations: University of Maryland,College Park MD, USA; IEN Galileo Ferraris Torino;
University of Sannio, Benevento, Italy
- Forces in polarizable materials
- The formulation of the problem of forces in macroscopic polarizable materials
(dielectric and magnetic) has been considered. This problem is quite controversial
since one has to make assumptions to distinguish between short range contact forces and
long range Maxwellian forces. The correct formulation of the problem is prerequisite
for developing appropriate computational schemes. Numerical solution by finite elements
has been carried out in the case of fluid materials.
- Spinstand imaging (1998-1999)
- A new technique of magnetic imaging on a spin stand has been developed. In this technique, raw
image acquisition is performed by scanning a target area of a disk by a conventional
magneto-resistive MR-read head in two orthogonal along- and cross-track directions. Due to the
nonlocalized nature of the MR reading head in the cross-track direction, image reconstruction is
needed in order to retrieve the actual distribution of magnetization.
Cooperations: Laboratory for Physical Science, College Park MD, USA, University of Maryland,College Park MD, USA.
- Particle accelerator Physics (1994 - 2001)
- Computational study of the longitudinal instability in storage ring by
using nonlinear fluid model of the coasting beam. Cooperation: GSI Darmstadt, Germany.
- Performance of Plasma Lenses in presence of nonlinear magnetic field profile.
Cooperation: GSI Darmstadt, Germany
- Cellular Networks (1995-2001)
- Cellular networks are electronic analog elctrical networks composed by a lattice of
identical simple (first or second order) nonlinear circuits. The lattice structure
and the nonlinearity give rise to nontrivial behaviour which leads to pattern formations
and information propagation which can be used for fast image processing, and
analog simulator of continuous fenomena. Cooperation: EPFL Lausanne, Switzerland.
Future Research Objectives and Perspectives
- Coupled Problems
- Spintronics. This is one the the most promising area of research in applied magnetics.
The problem is to describe the interaction of magnetization with electric currents
passing trough the system. Classical examples of spintronics systems are spin-valve
and spintorque multilayers. In the very next future will be important to develop computational
schemes based on the coupling between magnetic spin models and micromagnetics with the
problem of electric current distribution. In some sense, the problem is analogous to
the modeling of semiconductor devices where one has to determine the distribution of
carriers and the configuration of the electric current density.
- Magnetoelastic materials, Piezo-electric materials. Materials which exhibit coupling of magnetic
or electrical properties with elastic or plastic properties are the focus of considerable research.
The analysis of this materials requires the evaluation of forces and stresses induced by the
magnetic field and by the magnetization state and this is indeed a very controversial issue.
Reliable computational schemes for elastic-electromagnetic phenomena still represent a formidable
and very challenging problem. Nevertheless any step forward in this direction
will have a considerable impact on the ability to design devices.
- Magnetic Materials Multiscale Modeling
- From mesoscale (nanometers, sub-micrometers) to macroscale (millimiters).
Developing computational scheme for treating problems
which involves spatial scale from nanometers to millimeters. In this respect, it is important
to investigate the connection between the Micromagnetic description and the phenomenological
description based on Preisah-like models of the magnetic materials.
This investigation should lead to computational procedure to describe devices which include
macroscopic parts but, nevertheless, are considerable affected by nanoscale details
(for instance magnetic configuration at pole tips of thin-film magnetic yokes.)
- Multiscale analysis from mesoscale to macroscale would be also instrumental in the
analysis of nanostructured materials.
An important example is the case of materials constituted by arrays
of ferromagnetic particles in nonmagnetic media. In this case, the micromagnetic theory coupled
with suitable homogeneization techniques should be used to design appropriate computational procedures
to predict the macroscopic behaviour of the system.
- Computational Nonlinear Physics
- Computations which involve thermodynamics and Statistical Mechanics of Systems with Hysteresis
and in far-from-equilibrium conditions. The research objectives mentioned above have to face a
fundamental difficulty. The presence of hysteresis, multi-stability, thermal
fluctuations and possibly coupling of energy terms of different nature (e.g. mechanical, magnetic,
dielectric, etc.). The mesoscopic and macroscopic descriptions
of these kind of problems is very far to be systematized.
At the same time, trustable computations should be based on relatively estabilished results.
One classical difficulties in mesoscopic far-from-equilibrium simulations is the issue of including
finite temperature effects and how to describe thermal fluctuations. This issue, which
is very general in nature, has a very important role in most computational physics recent problems.
- Computational tools to study bifurcations, coherent structures, solitons, chaotic dynamics.
The dynamics of far-from-equilibrium systems is most of the time nonlinear in nature and may
exhibit a rich variety of nonlinear phenomena. This is particularly important when one has
to study open systems (like nanomagnets traversed by currents) where stationary state are
strongly depend on non-conservative far-from-equilibrium external constraints.