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1
Content available remote

Surface Magnetostriction Model for MagNEMS

100%
Szumiata T., Gzik-Szumiata M.
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vol. 126
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issue 1
200-201
EN
In this work the influence of surface roughness on magnetostrictive nano-actuator parameters has been analyzed theoretically. A mechanical and magnetoelastic behavior of investigated cantilever bimorphic system has been described in the frame of the simple analytical model. Realistic material parameters have been incorporated into the model for high-magnetostrictive galfenol (Fe-Ga) thin films on silicon substrate. It has been shown that for 5 nm thick galfenol film a flat surface magnetostrictive effects modify the cantilever deflection and force only by 3%, whereas in the case of rough surface this influence increases to about 15%, when dimensions of roughness steps are comparable to the distances between them.
2
Content available remote

Thermal Compensation Model of Magnetic Circuits with Modern Magnetic Materials

100%
Szumiata T., Gzik-Szumiata M.
Acta Physica Polonica A
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2015
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vol. 127
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issue 2
650-652
EN
In this work a quantitative analysis of thermal compensation has been performed for a magnetic circuit producing magnetic field in the air gap. The considered system consists of Sm₃Co₁₇ type permanent magnet (as a source of magnetic field), nanocrystalline FINEMET alloy (as ultra-soft magnetic medium) and Fe-Ni low Curie temperature compensative material (as a magnetic shunt). Distribution of magnetic field induction in the circuit has been calculated numerically within standard one-dimensional approximation, considering nonlinearities of compensative material as well as demagnetization susceptibility of permanent magnet. It has been theoretically predicted, that an appropriate choice of the compensative element thickness improves significantly thermal stability of magnetic field in the air gap.
3
Content available remote

The Magnetic Specific Heat of the BEG Model

100%
Gzik-Szumiata M., Balcerzak T.
Acta Physica Polonica A
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2000
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vol. 97
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issue 5
939-942
EN
The magnetic contribution to the specific heat of the Blume-Emery-Griffiths model with spin-one is studied by the cluster variational method in pair approximation. The nearest neighbour correlation functions are taken into account. The temperature dependencies of the specific heat are calculated and discussed in the context of the phase diagrams obtained recently for the thin film with bilayer geometry.
4
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Model of Anisotropic Electrical Resistivity in Rough Thin Films

100%
Szumiata T., Gzik-Szumiata M.
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issue 5
859-860
EN
In this work a new model of electrical resistivity is proposed in order to study the relationship between surface roughness geometry and thin films resistivity. The model is based on the numerical dynamic averaging of electron mean free path over whole simulated structure of rough film. For current-in-plane configuration the resistivity increases with decreasing film thickness faster than for current-perpendicular-to-plane one. Our simulations showed that big roughness depth and fine in-plane spatial period of roughness are crucial factors increasing the resistivity of ultrathin metallic layers.
5
Content available remote

Modelling of Spin-Dependent Mechanical Friction at Atomic Level

81%
Gzik-Szumiata M., Szumiata T., Morozow D.
Acta Physica Polonica A
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2018
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vol. 133
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issue 3
713-715
EN
In this work a simple 2D model of pseudostatic friction at atomic level has been prepared, in the frame of which both Lennard-Jones potential and spin-dependent term of exchange interaction has been included. As an example, it has been demonstrated, that for iron both average lateral and normal forces between atoms of "base" and "slider" in the tribological node are altered through the change of relative direction of spins, by over a dozen of percent, when the interatomic distance is comparable to the lattice constant. Spin-dependent correction of atomic-level friction coefficient has been estimated.
6
Content available remote

Modeling of Magnetic Hyperfine Field Distribution for Spherical Nanoparticles of bcc Structure

71%
Szumiata T., Gzik-Szumiata M., Brzózka K., Gawroński M., Górka B.
Acta Physica Polonica A
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2008
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vol. 113
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issue 1
537-540
EN
We propose a simple model for temperature evolution of magnetic hyperfine field distribution of spherical bcc Fe nanoparticles. We performed mean field approximation calculations of mean spin value in each spherical shell of nanoparticle. Considering magnetic hyperfine field values reported for iron thin films we predicted possible values of hyperfine fields in the internal and surface region of the particles as a function of temperature.
7
Content available remote

Stress Monitoring in Steel Elements via Detection of AC Magnetic Permeability Changes

52%
Szumiata T., Hibner K., Dziewiecki K., Mazur Z., Gockiewicz A., Gzik-Szumiata M., Górka B., Witoś M.
Acta Physica Polonica A
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2018
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vol. 133
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issue 3
719-721
EN
The influence of mechanical stress on low frequency AC magnetic permeability was studied. The cold-drawn bars with C45 steel were subjected to investigation. The tensile stress (within elastic regime) was applied by means of material testing machine. Simple measuring system was assembled, which consisted of: function generator with magnetizing coil, detection coil and precise AC voltmeter. The registered changes of induced voltage were proportional to the change of magnetic permeability of the stretched rods. The obtained results were almost frequency-independent due to low frequency limit (250-500 Hz, weak eddy currents, no spin-origin energy dissipation). A significant magneto-mechanical hysteresis was observed slightly evolving from cycle to cycle with tendency of stabilization. The extension of basic Stoner-Wohlfarth model of magnetic permeability allowed to fit the data reproducing hysteretic behavior and considering the relaxation of the internal stress. The proposed, low-cost method is suitable in the industrial applications for stress control in large-sized steel elements.
8
Content available remote

Mössbauer and Magnetic Study of Fe+Vitroperm+Plastic System

52%
Brzózka K., Kollár P., Szumiata T., Sovak P., Füzer J., Fáberová M., Bureš R., Górka B., Gawroński M., Gzik-Szumiata M.
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vol. 126
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issue 1
148-149
EN
Phase composition and magnetization curves of the soft magnetic composites, fabricated by compaction of several kinds of powders mixed in various proportions, have been investigated by means of conversion electron Mössbauer spectroscopy and an alternating gradient force magnetometry. The results point to significant quantity of iron oxides - hematite and magnetite - at the surface of the samples. After the rubbing of thin surface layer, the relative content of oxides was distinctly reduced. Magnetic measurements revealed very similar characteristics of hysteresis curves for all the investigated materials.
9
Content available remote

Magnetism and Structure Evolution in Ni-Zn Ferrites Thin Films - CEMS Study

52%
Szumiata T., Gzik-Szumiata M., Brzózka K., Górka B., Gawroński M., Javed A., Farman K., Fatima T.
Acta Physica Polonica A
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2017
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vol. 131
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issue 4
836-838
EN
In this work, a ⁵⁷Fe conversion electron Mössbauer spectrometry and X-ray diffraction have been utilized in order to investigate the structural and magnetic order in 500 nm thick Ni-Zn ferrite films deposited on Si(100) substrate by laser ablation. Considering the contributions of the conversion electron Mössbauer subspectra corresponding to the tetrahedral (A) and octahedral (B) sites, the spinel inversion parameter in [Zn_{x}Fe_{1-x}]^{A}[Ni_{1-x}Fe_{1+x}]^{B}O₄ films has been estimated. The hyperfine field (B_{hf}) values in the investigated Ni-Zn ferrites thin films are about 5-8% smaller than those of bulk ferrites, which could be a sign of thermal magnetic relaxations due to the size effects. The distribution of hyperfine magnetic field directions was found to be affected by perpendicular anisotropy.
10
Content available remote

Influence of Milling and Compaction Processes οn Magnetic Properties of FeCo Powder

52%
Szumiata T., Gzik-Szumiata M., Brzózka K., Gawroński M., Górka B., Kollár P., Olekšáková D., Polański K., Szmaja W.
Acta Physica Polonica A
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2009
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vol. 115
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issue 1
403-405
EN
Magnetic and structural studies were performed on Fe_{50}Co_{50} material. The samples (disk-shaped, diameter: 10 mm, thickness: 2.5 mm) were fabricated by compaction of powder under pressure of 800 MPa for 5 min at temperatures 300-600°C. The powder was obtained by milling of Fe_{50}Co_{50} alloy swarfs in high-energy planetary mill. The milling time varied from 1 h to 40 h. In the course of milling process the mean size of alloy pieces was decreasing from about 0.5 mm to 0.05 mm (scanning electron microscopy), which provided more compact structure after compression. The annealing process during compaction strongly reduces a coercive field of the samples. Parameters of conversion electron Mössbauer spectra are almost the same for all samples, which points to not significant changes of atomic and magnetic order after milling and compacting.
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