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J. Gieraltowski

Publications and source records attributed to J. Gieraltowski.

At least 19 recordsLinked to original sources
arXiv2021

Information theory based Electron Paramagnetic Resonance dating

Chronometric dating is becoming increasingly important in areas such as the Origin and evolution of Life on Earth and other planets, Origin and evolution of the Earth and the Solar System... Electron Spin Resonance (ESR) dating is based on exploiting effects of contamination by chemicals or ionizing radiation, on ancient matter through its absorption spectrum and lineshape. Interpreting absorption spectra as probability density functions (pdf), we use the notion of Information Theory (IT) distance allowing us to position the measured lineshape with respect to standard limiting pdf's (Lorentzian and Gaussian). This paves the way to perform dating when several interaction patterns between unpaired spins are present in geologic, planetary, meteorite or asteroid matter namely classical-dipolar (for ancient times) and quantum-exchange-coupled (for recent times). In addition, accurate bounds to age are provided by IT from the evaluation of distances with respect to the Lorentz and Gauss distributions. Dating arbitrary periods of times~\cite{Anderson} and exploiting IT to introduce rigorous and accurate date values might have interesting far reaching implications not only in Geophysics, Geochronology~\cite{Bahain}, Planetary Science but also in Mineralogy, Archaeology, Biology, Anthropology~\cite{Aitken}, Paleoanthropology~\cite{Taylor,Richter}...

physics.data-an↗
arXiv2016

Electronic control of magnonic and spintronic devices

Nanometric magnonic and spintronic devices need magnetic field control in addition to conventional electronic control. In this work we review ways to replace magnetic field control by an electronic one in order to circumvent appearance of stray magnetic fields or the difficulty of creating large magnetic fields over nanometric distances. Voltage control is compared to current control and corresponding devices are compared from their energetic efficiency point of view.

cond-mat.mtrl-sci↗
arXiv2013

Angular Preisach analysis of Hysteresis loops and FMR lineshapes of ferromagnetic nanowire arrays

Preisach analysis is applied to the study of hysteresis loops measured for different angles between the applied magnetic field and the common axis of ferromagnetic Nickel nanowire arrays. When extended to Ferromagnetic Resonance (FMR) lineshapes, with same set of parameters extracted from the corresponding hysteresis loops, Preisach analysis shows that a different distribution of interactions or coercivities ought to be used in order to explain experimental results. Inspecting the behavior of hysteresis loops and FMR linewidth versus field angle, we infer that angular dependence might be exploited in angle sensing devices that could compete with Anisotropic (AMR) or Giant Magnetoresistive (GMR) based devices.

cond-mat.mtrl-sci↗
arXiv2013

Temperature dependent anisotropy and elastic effects in ferromagnetic nanowire arrays

Temperature dependent Ferromagnetic Resonance measurements performed as a function of diameter on Nickel nanowire arrays reveal several interesting features in these systems. With diameter decrease from 100 nm to 15 nm, a transition induced by surface anisotropy increase is observed at 50 nm in easy axis orientation from parallel to perpendicular with respect to individual nanowire geometric axis. Analysis of resonance field $H_{res}$ temperature variation (between liquid Helium and room temperature) reveals underlying strong magneto-elastic effects in small and large diameter nanowire arrays with potential applications in recording and spintronics.

cond-mat.mtrl-sci↗
arXiv2010

Geometric signature of reversal modes in ferromagnetic nanowires

Magnetic nanowires are a good platform to study fundamental processes in Magnetism and have many attractive applications in recording such as perpendicular storage and in spintronics such as non-volatile magnetic memory devices (MRAM) and magnetic logic devices. In this work, nanowires are used to study magnetization reversal processes through a novel geometric approach. Reversal modes imprint a definite signature on a parametric curve representing the locus of the critical switching field. We show how the different modes affect the geometry of this curve depending on the nature of the anisotropy (uniaxial or cubic anisotropy), demagnetization and exchange effects. The samples we use are electrochemically grown Nickel and Cobalt nanowires.

physics.comp-ph↗
arXiv2008

Structural and angular dependence of coercivity and magnetic remanence of electrochemical ferromagnetic nanowires

A novel method for controlling nanowire magnetic properties and growth from filling time profile is presented. The wires are grown with an electrodeposition method ("Template synthesis") with a wide selection of pore diameters. We show that stray-fields presence in ferromagnetic nanowires are entirely dependent on the nanowire diameter. Besides a crossover effect in the reversal mechanism is observed with change in diameter. In this work, theory and experiment agree and confirm that according to the variety of hysteresis loop measured, about four ranges of values of pore diameter control the orientation of nanowire magnetization easy axis with respect to the geometrical axis.

cond-mat.mtrl-sci↗
arXiv2008

The Stoner-Wohlfarth model of Ferromagnetism: Static properties

Recent advances in high-density magnetic storage and spin electronics are based on the use of magnetic materials along with conventional microelectronic materials (metals, insulators and semiconductors). The unit information (bit) is stored as a magnetization state in some ferromagnetic ma rial (FM) and controlled with an external field altering the magnetization state. As device size is shrinking steadily toward the nanometer and the need to incr se its bandwidth prevails, racing toward higher frequencies is getting even more cha enging. In magnetic systems, denser storage leads to finer magnetic grains and small size leads to single magnetic domain physics. The Stoner-Wohlfarth model is the simplest model that describes adequately the physics of fine magnetic grains containing single domains and where magnetization state changes by rotation or switching (abrupt reversal). The SW model is reviewed and discussed with its consequences and potential app cations in the physics of magnetism and spin electronics.

physics.class-ph↗
arXiv2008

The Stoner-Wohlfarth model of Ferromagnetism: Dynamic and Statistical properties

The physics of magnetic state change or reversal in single domain magnetic grains (called Stoner particles) is interesting from the fundamental as well as the applied points of view. A change in magnetization can be finely tuned with a specific time variation o f an externally applied magnetic field. It may also occur naturally (without application of a field) at very low tempe rature with quantum tunneling and at higher temperature with thermal excitation. The optimal (usually shortest) time altering the magn etisation along with the smallest applied magnetic field are sought in technological applications s uch as high-density reading or writing of information, spintronics, quantum inform ation and quantum communication systems. This work reviews the magnetization change with a time dependent field and tem perature and discusses the time it takes to alter the magnetization as a function of the control parameter chosen, temperature and material parameters.

physics.class-ph↗
arXiv2007

Effect of the metal-to-wire ratio on the high-frequency magnetoimpedance of glass-coated CoFeBSi amorphous microwires

High frequency [1-500 MHz] measurements of the magnetoimpedance (MI) of glass-coated Co$_{69.4}$Fe$_{3.7}$B$_{15.9}$Si$_{11}$ microwires are carried out with various metal-to-wire diameter ratios. A twin-peak, anhysteretic behaviour is observed as a function of magnetic field. A maximum in the normalized impedance, $ΔZ$/$Z$, appears at different values of the frequency $f$, 125, 140 and 85 MHz with the corresponding diameter ratio $p$ = 0.80, 0.55 and 0.32. We describe the measurement technique and interpret our results with a thermodynamic model that leads to a clearer view of the effects of $p$ on the maximum value of MI and the anisotropy field. The behavior of the real and imaginary components of impedance is also investigated; they display a resonance that becomes a function of the DC field $H_{DC}$ for values larger or equal to $H_{K}$ the circumferential anisotropy field for each $p $ value. These results are interpreted in terms of a rotation model of the outer shell magnetization.

cond-mat.mtrl-sci↗
arXiv2006

Magnetic domain-walls and the relaxation method

The relaxation method used to solve boundary value problems is applied to study the variation of the magnetization orientation in several types of domain walls that occur in ferromagnetic materials. The algorithm is explained and applied to several cases: the Bloch wall in bulk magnetic systems, the radial wall in cylindrical wires and the Néel wall in thin films

physics.class-ph↗
arXiv2005

Helical anisotropy and magnetoimpedance of CoFeSiB wires under torsional stress

Recent measurements of the magnetoimpedance (at a fixed frequency of 1 MHz) of cobalt-rich wires subjected to torsion stress show an asymmetry as a function of torsion angle stemming from residual anisotropies induced during wire fabrication. We interpret these measurements with a simple model based on the competition between a circumferential magnetic anisotropy and another one induced by torsional and residual stress. This allows extraction of the physical parameters of the wire and explains the positive and negative torsion cases. The agreement between theoretical and experimental results provides a firm support for the model describing the behaviour of the anisotropy field versus static magnetic field for all torsion angles.

cond-mat.mtrl-sci↗
arXiv2004

Metal-to-glass ratio and the Magneto-Impedance of glass-covered CoFeBSi microwires at high frequencies

High frequency [1-500 MHz] measurements of the Magneto-Impedance (MI) of glass-covered Co$_{69.4}$Fe$_{3.7}$B$_{15.9}$Si$_{11}$ microwires are carried out with various metal-to-wire diameter ratios. A twin-peak, anhysteretic behaviour is observed as a function of magnetic field. A maximum in $ΔZ/Z$ appears at different values of the frequency $f$, 125, 140 and 85 MHz with the corresponding diameter ratio $p$ = 0.80, 0.55 and 0.32. We describe the measurement technique and interpret our results with a thermodynamic model that leads to a clearer view of the effects of $p$ on the maximum value of MI and the anisotropy field.

cond-mat.mtrl-sci↗
arXiv2003

GRAPPA: Grid Access Portal for Physics Applications

Grappa is a Grid portal effort designed to provide physicists convenient access to Grid tools and services. The ATLAS analysis and control framework, Athena, was used as the target application. Grappa provides basic Grid functionality such as resource configuration, credential testing, job submission, job monitoring, results monitoring, and preliminary integration with the ATLAS replica catalog system, MAGDA. Grappa uses Jython to combine the ease of scripting with the power of java-based toolkits. This provides a powerful framework for accessing diverse Grid resources with uniform interfaces. The initial prototype system was based on the XCAT Science Portal developed at the Indiana University Extreme Computing Lab and was demonstrated by running Monte Carlo production on the U.S. ATLAS test-bed. The portal also communicated with a European resource broker on WorldGrid as part of the joint iVDGL-DataTAG interoperability project for the IST2002 and SC2002 demonstrations. The current prototype replaces the XCAT Science Portal with an xbooks jetspeed portlet for managing user scripts.

cs.DC↗
arXiv2003

Giant magnetoimpedance in Vitrovac amorphous ribbons over [0.3-400 MHz] frequency range

Giant magneto impedance (GMI) effect for as-cast Vitrovac$^{\textrm{\scriptsize\textregistered}}$ amorphous ribbons (Vacuumschmelze, Germany) in two configurations (parallel and normal to the ribbon axis) is studied over the frequency range [0.3-400 MHz] and under static magnetic fields -160 Oe $< H_{dc} < $+160 Oe. A variety of peak features and GMI ratio values, falling within a small field range, are observed and discussed.

cond-mat.mtrl-sci↗
arXiv2003

Giant Magneto-Impedance and its Applications

The status of Giant Magneto-Impedance effect is reviewed in Wires, Ribbons and Multilayered Soft Ferromagnetic Thin Films. After establishing the theoretical framework for the description of the effect, and the constraints any material should have in order to show the effect, experimental work in Wires, Ribbons and Multilayered Thin Films is described. Existing and potential applications of the effect in Electronics and Sensing are highlighted.

physics.ins-det↗
arXiv2002

Magnetic and Transport Properties of NiFe/SiO_{2}/NiFe Trilayers

Magnetic coupling between Ni_{81}Fe_{19} double thin films separated by an insulating SiO_{2} spacer layer is investigated with structural measurements, cross sectional imaging, magnetization measurements (BH loop) and transport under the conditions of variable spacer thickness ranging from 0 to 5000 Angstroms. We investigate several models to explain the coercivity variation with spacer thickness as well as the transport measurements.

cond-mat.mtrl-sci↗