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Full-Text Articles in Physics

Magnetocrystalline Anisotropy In Cobalt Based Magnets: A Choice Of Correlation Parameters And The Relativistic Effects, Manh Cuong Nguyen, Yong-Xin Yao, Cai-Zhuang Wang, Kai-Ming Ho, Vladimir P. Antropov Apr 2018

Magnetocrystalline Anisotropy In Cobalt Based Magnets: A Choice Of Correlation Parameters And The Relativistic Effects, Manh Cuong Nguyen, Yong-Xin Yao, Cai-Zhuang Wang, Kai-Ming Ho, Vladimir P. Antropov

Ames Laboratory Accepted Manuscripts

The dependence of the magnetocrystalline anisotropy energy (MAE) in MCo5 (M  =  Y, La, Ce, Gd) and CoPt on the Coulomb correlations and strength of spin orbit (SO) interaction within the GGA  +  U scheme is investigated. A range of parameters suitable for the satisfactory description of key magnetic properties is determined. We show that for a large variation of SO interaction the MAE in these materials can be well described by the traditional second order perturbation theory. We also show that in these materials the MAE can be both proportional and negatively proportional to the orbital moment anisotropy (OMA) of Co ...


Recycled Sm-Co Bonded Magnet Filaments For 3d Printing Of Magnets, Helena A. Khazdozian, J. Sebastian Manzano, Kinjal Gandha, Igor I. Slowing, Ikenna C. Nlebedim Jan 2018

Recycled Sm-Co Bonded Magnet Filaments For 3d Printing Of Magnets, Helena A. Khazdozian, J. Sebastian Manzano, Kinjal Gandha, Igor I. Slowing, Ikenna C. Nlebedim

Ames Laboratory Accepted Manuscripts

Recycling of rare earth elements, such as Sm and Nd, is one technique towards mitigating long-term supply and cost concerns for materials and devices that depend on these elements. In this work recycled Sm-Co powder recovered from industrial grinding swarfs, or waste material from magnet processing, was investigated for use in preparation of filament for 3D printing of bonded magnets. Recycled Sm-Co powder recovered from swarfs was blended into polylactic acid (PLA). Up to 20 vol.% of the recycled Sm-Co in PLA was extruded at 160°C to produce a filament. It was demonstrated that no degradation of magnetic properties ...


Thermal Effects On The Magnetic Properties Of Titanium Modified Cobalt Ferrite, Ikenna C. Nlebedim, David C. Jiles Jan 2015

Thermal Effects On The Magnetic Properties Of Titanium Modified Cobalt Ferrite, Ikenna C. Nlebedim, David C. Jiles

Electrical and Computer Engineering Publications

The temperature dependence of the magnetic properties of titanium modified cobalt ferrite is presented. The change of maximum magnetization obtained at H ≈ 2.4 MA/m between any two temperatures increases systematically with composition, which is desirable for applications in devices. Variation in magnetocrystalline anisotropy and coercivity were different from previous studies on cation substituted cobalt ferrite. At lower concentrations, the effect of lower thermal energy dominated the effect of non-magnetic cation substitutions in controlling the anisotropy.The reverse was the case at higher concentrations. The temperature dependence of coercivity is dominated by the contribution of magnetocrystalline anisotropy to coercivity ...


Structural, Magnetic, And Magnetoelastic Properties Of Magnesium Substituted Cobalt Ferrite, Cajetan Ikenna Nlebedim, Ravi L. Hadimani, Ruslan Prozorov, David C. Jiles Jan 2013

Structural, Magnetic, And Magnetoelastic Properties Of Magnesium Substituted Cobalt Ferrite, Cajetan Ikenna Nlebedim, Ravi L. Hadimani, Ruslan Prozorov, David C. Jiles

Electrical and Computer Engineering Publications

The effects of substituting Mg on the structural, magnetic, and magnetostrictive properties ofcobalt ferrite have been investigated. Comparable values of lattice parameter were obtained for the Mg-substituted samples. Saturation magnetization continuously decreased with increase inMg concentration. Peak-to-peak magnetostriction amplitude and strain sensitivity had a similar dependence on Mg concentration.


Magnetism Of (Dy0.5er0.5)Al2 Single Crystal In Ac And Dc Magnetic Fields, Evgenii M. Levin, Karl A. Gschneidner Jr., Thomas A. Lograsso, Deborah L. Schlagel Aug 2006

Magnetism Of (Dy0.5er0.5)Al2 Single Crystal In Ac And Dc Magnetic Fields, Evgenii M. Levin, Karl A. Gschneidner Jr., Thomas A. Lograsso, Deborah L. Schlagel

Ames Laboratory Publications

The temperature (4.2–90 K), ac magnetic field (1.25–50 Oe), frequency (5–125 Hz), and bias dc magnetic field (0–10 kOe) dependencies of the real and imaginary components of the ac magnetic susceptibility, and the temperature (4.2–250 K) and dc magnetic field(0.1–50 kOe) dependencies of the dc magnetic susceptibility and magnetization of a(Dy0.5Er0.5)Al2 single crystal have been studied. Isothermal magnetization measurement in a dc magnetic field indicates that (Dy0.5Er0.5)Al2 orders ferromagnetically at 37 K. The ac ...


Variation Of Magnetostriction With Temperature In Tb5si2.2ge1.8 Single Crystal, A. P. Ring, H. L. Ziegler, Thomas A. Lograsso, Deborah L. Schlagel, J. E. Snyder, David C. Jiles Apr 2006

Variation Of Magnetostriction With Temperature In Tb5si2.2ge1.8 Single Crystal, A. P. Ring, H. L. Ziegler, Thomas A. Lograsso, Deborah L. Schlagel, J. E. Snyder, David C. Jiles

Ames Laboratory Conference Papers, Posters, and Presentations

The Tb5(SixGe4−x) alloy system is similar to the better known Gd5(SixGe4−x), except it has a more complex magnetic and structural phase diagram. Gd5(SixGe1−x)4 has received much attention recently due to its giant magnetocaloric effect, colossal magnetostriction and giant magnetoresistance in the vicinity of a first order combined magnetic-structural phase transition. The magnetostriction changes that accompany the phase transitions of single crystal Tb5(Si2.2Ge1.8) have been investigated at temperatures between 20 and150 K by measurements of ...


Temperature Dependence Of The Magnetic Anisotropy And Magnetostriction Of Fe100−Xgax (X = 8.6, 16.6, 28.5), A. E. Clark, M. Wun-Fogle, J. B. Restorff, Kevin W. Dennis, Thomas A. Lograsso, R. William Mccallum May 2005

Temperature Dependence Of The Magnetic Anisotropy And Magnetostriction Of Fe100−Xgax (X = 8.6, 16.6, 28.5), A. E. Clark, M. Wun-Fogle, J. B. Restorff, Kevin W. Dennis, Thomas A. Lograsso, R. William Mccallum

Ames Laboratory Conference Papers, Posters, and Presentations

The temperature dependence of the lowest order magnetic anisotropy constant K1 and the lowest order saturation magnetostriction constant, (3/2)λ100, were measured from 4 K to 300 K for Fe91.4Ga8.6,Fe83.4Ga16.6, and Fe71.5Ga28.5 and were compared to the normalized magnetization power law, ml(l+1)/2. Fe91.4Ga8.6 maintains the magnetostriction anomaly of Fe (dλ100/dT>0) and K1 is a reasonable fit to the ml(l+1)/2power law with ...


Magnetic Anisotropy And Phase Transitions In Single-Crystal Tb5(Si2.2ge1.8), M. Han, J. E. Snyder, W. Tang, Thomas A. Lograsso, Deborah L. Schlagel, David C. Jiles May 2005

Magnetic Anisotropy And Phase Transitions In Single-Crystal Tb5(Si2.2ge1.8), M. Han, J. E. Snyder, W. Tang, Thomas A. Lograsso, Deborah L. Schlagel, David C. Jiles

Ames Laboratory Conference Papers, Posters, and Presentations

The Tb5(SixGe4−x) alloy system has many features in common with the Gd5(SixGe4−x)system although it has a more complex magnetic and structural phase diagram. This paper reports on the magnetic anisotropy and magnetic phase transition of single-crystalTb5(Si2.2Ge1.8) which has been investigated by the measurements of M-H and M-T along the a, b, and c axes. The variation of 1/χ vs T indicates that there is a transition from paramagnetic to ferromagnetic at Tc = 110 K. Below this ...


Magnetostriction And Elasticity Of Body Centered Cubic Fe100−Xbex Alloys, A. E. Clark, M. Wun-Fogle, J. B. Restorff, Thomas A. Lograsso, G. Petculescu Jun 2004

Magnetostriction And Elasticity Of Body Centered Cubic Fe100−Xbex Alloys, A. E. Clark, M. Wun-Fogle, J. B. Restorff, Thomas A. Lograsso, G. Petculescu

Ames Laboratory Conference Papers, Posters, and Presentations

Magnetostriction measurements from 77 K to room temperature on oriented (100) and (110) disk samples of Fe93.9Be6.1 and Fe88.7Be11.3 reveal substantial increases in λ100compared to iron. For the 11.3% alloy, λ100=110 ppm, a sixfold increase above that of α-Fe. For the 6.1% alloy, λ100=81 ppm, ∼40% and ∼170% greater than λ100 of comparable Fe–Ga and Fe–Al alloys, respectively, for H=15 kOe. Large differences exist between the values of λ100 and λ111 (λ100>0, λ111 ...


Magnetic Field Induced Phase Transitions In Gd5(Si1.95ge2.05) Single Crystal And The Anisotropic Magnetocaloric Effect, H. Tang, A. O. Pecharsky, Deborah L. Schlagel, Thomas A. Lograsso, Vitalij K. Pecharsky, Karl A. Gschneidner Jr. May 2003

Magnetic Field Induced Phase Transitions In Gd5(Si1.95ge2.05) Single Crystal And The Anisotropic Magnetocaloric Effect, H. Tang, A. O. Pecharsky, Deborah L. Schlagel, Thomas A. Lograsso, Vitalij K. Pecharsky, Karl A. Gschneidner Jr.

Ames Laboratory Conference Papers, Posters, and Presentations

Magnetization measurements using a Gd5(Si1.95Ge2.05) single crystal with the magnetic field applied along three crystallographic directions, [001], [010] and [100], were carried out as a function of the applied field (0–56 kOe) at various temperatures (∼5–320 K). The magnetic field (H)–temperature (T) phase diagrams were constructed for theGd5(Si1.95Ge2.05) single crystal with field along the three directions. A small anisotropy was observed. The magnetocaloric effect was calculated from isothermal magnetization data, and the observed anisotropy correlates with the HT phase diagrams. The results ...


Superparamagnetic Magnetization Equation In Two Dimensions, David C. Jiles, S. J. Lee, J. M. Kenkel, K. L. Metlov Aug 2000

Superparamagnetic Magnetization Equation In Two Dimensions, David C. Jiles, S. J. Lee, J. M. Kenkel, K. L. Metlov

Ames Laboratory Publications

An equation for the dependence of magnetization on magnetic field in the case of two-dimensional (base plane) anisotropy has been derived. The resulting equation is expressed as an infinite series of modified Bessel functions, unlike the elementary function expressions that are applicable to the one-dimensional (axially anisotropic) and three-dimensional (isotropic) cases. Nevertheless, in the low-field limit, the series can be effectively truncated to give an approximate solution, while, in the high-field limit, an alternative expression has been derived which represents the limiting function as the field strength tends to infinity. The resulting expressions can be used to describe the superparamagnetic ...


Application Of The Preisach And Jiles–Atherton Models To The Simulation Of Hysteresis In Soft Magnetic Alloys, M. Pasquale, G. Bertotti, David C. Jiles, Y. Bi Apr 1999

Application Of The Preisach And Jiles–Atherton Models To The Simulation Of Hysteresis In Soft Magnetic Alloys, M. Pasquale, G. Bertotti, David C. Jiles, Y. Bi

Ames Laboratory Publications

his article describes the advances in unification of model descriptions of hysteresis in magnetic materials and demonstrates the equivalence of two widely accepted models, the Preisach (PM) and Jiles–Atherton (JA) models. Recently it was shown that starting from general energy relations, the JA equation for a loop branch can be derived from PM. The unified approach is here applied to the interpretation of magnetization measured in nonoriented Si–Fe steels with variable grain size ⟨s⟩, and also in as-cast and annealed Fe amorphous alloys. In the case of NO Fe–Si, the modeling parameter k defined by the volume ...


Generalization Of Hysteresis Modeling To Anisotropic Materials, A. Ramesh, David C. Jiles, Y. Bi Apr 1997

Generalization Of Hysteresis Modeling To Anisotropic Materials, A. Ramesh, David C. Jiles, Y. Bi

Materials Science and Engineering Publications

An extension to the model of hysteresis has been presented earlier which included the effect of anisotropy in the modeling of the anhysteretic magnetization curves of uniaxially anisotropic single crystalline materials. Further exploration of this extension shown here considers different kinds of crystal anisotropy in materials. Theory considers that the differential susceptibility at any given field is determined by the displacement of the prevailing magnetization from the anhysteretic magnetization. Thus, it has been shown that the effect of anisotropy on magnetic hysteresis in materials can be incorporated into the model of hysteresis through the anisotropic anhysteretic. This extension is likely ...