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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
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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.
4
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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.
5
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Dipolar Contributions to Magnetoelastic Energy of Crystal Grains with Interfaces

81%
Szumiata T., Żuberek R., Szymczak H., Gonzalez J.
Acta Physica Polonica A
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2000
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vol. 97
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issue 3
531-534
EN
The magnetic anisotropy and magnetostriction in nanocrystalline grains in non-magnetic or magnetic matrix (nanoparticles or nanocrystalline materials) differ from their bulk properties. The interactions between atoms at the interface play the important role in these magnetic properties. In this paper the magnetic dipolar contribution to magnetostriction energy has been calculated for spherical crystal grains (of bcc and fcc symmetry) with interface layer of atoms possessing different magnetic moment. Total magnetoelastic energy of the sphere-interface system is a sum of magnetoelastic energy of the sphere, energy of the interactions between the sphere and the interface and also the energy of the interface. It was shown that magnetoelastic energy depends on the sphere size and interface thickness.
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
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Phase Composition and Magnetic Properties of Nanoperm Thin Films Doped with Yttrium

71%
Brzózka K., Sovák P., Szumiata T., Górka B., Gawroński M.
Acta Physica Polonica A
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2012
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vol. 121
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issue 5-6
1270-1272
EN
Thin films of Nanoperm alloys with partial substitution of iron by yttrium are the subject of investigations. The attention is fixed on the influence of yttrium substitution on structure and magnetic characteristics of the samples. The effect of film thickness is also considered. Conversion electron Mössbauer spectroscopy and magneto-optic Kerr effect were used to derive hyperfine parameters and coercive field, respectively. Coexistence of crystalline bcc-Fe phase and an amorphous one with diverse proportion was stated in most of the samples. It was found that surface and interface regions contribute to the magnetic properties of films.
8
Content available remote

Mössbauer Study of Magnetic Texture of Finemet-Type Ribbons

71%
Brzózka K., Sovák P., Górka B., Szumiata T., Gawroński M.
Acta Physica Polonica A
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2011
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vol. 119
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issue 1
33-36
EN
Magnetic texture of amorphous Finemet-type alloys substituted by Co, Ni, Mn, Ge and V was investigated by means of Mössbauer spectroscopy using various angular configurations. Samples in form of ribbons were manufactured by single-roller melt spinning technique. In most of investigated alloys some preference of alignment of atomic magnetic moments in-plane of sample is stated, except of some alloys substituted by germanium in which slight tendency to out-of plane spin orientation is proved.
9
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Local Structure and Magnetic Characteristics of FINEMET Alloys Substituted by Vanadium

62%
Brzózka K., Szumiata T., Gawroński M., Górka B., Sovák P., Pavlík G., Kolesár V.
Acta Physica Polonica A
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2008
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vol. 113
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issue 1
51-54
EN
Amorphous and nanocrystalline FINEMET-type alloys with vanadium addition up to 7 at% were investigated by the MÖssbauer spectroscopy and magnetic methods. The outcomes evidence alterations in grain structure, although the main effect is related to the changes in intergranular phase. This induces diminution of mean hyperfine field, saturation induction and Curie temperature as well as the increase in coercivity.
10
Content available remote

Structural and Magnetic Ordering in Fe-Ga Thin Films Examined by Mössbauer Spectrometry

62%
Szumiata T., Brzózka K., Gawroński M., Górka B., Javed A., Morley N., Gibbs M.
Acta Physica Polonica A
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2011
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vol. 119
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issue 1
21-23
EN
The detailed analysis of atomic and magnetic structure has been performed by Mössbauer spectroscopy for polycrystalline Fe_{80}Ga_{20} films of different thickness ranging from 20 nm to 200 nm. The films were deposited on Si(100) substrate using dual sputtering and evaporation method. Obtained CEMS spectra have been fitted with several Gaussian distributions of hyperfine magnetic field. The results point to the domination of BCC disordered A2 phase and the absence of DO_{3} and L1_{2} phases in the films. Both hyperfine parameters and lattice constant reveal anomaly for 40 nm thick sample - presumably due to the change of the internal stress. Spin texture evolves from in-plane to out-of-the-plane configuration with increasing thickness.
11
Content available remote

Finemet Thin Films Substituted by Chromium - CEMS and MOKE Study

62%
Brzózka K., Szumiata T., Sovák P., Górka B., Hibner K., Balcerski J.
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issue 5
794-796
EN
Conversion electron Mössbauer spectroscopy and magneto-optical Kerr effect were applied to investigate hyperfine interactions and macroscopic magnetic properties of Finemet-type thin films. Phase analysis as well as compositional evolution of hyperfine parameters and coercivity was performed in the range of chromium percentage 0 ≤ x ≤ 14. Essential differences in structure and hyperfine parameters were found for films of different chromium concentration. Coercivity shows non-monotonic dependence with minimal value at x = 5.
12
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.
13
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.
14
Content available remote

Phase Analysis of Magnetic Inclusions in Nanomaterials Based on Multiwall Carbon Nanotubes

52%
Brzózka K., Krajewski M., Małolepszy A., Stobiński L., Szumiata T., Górka B., Gawroński M., Wasik D.
Acta Physica Polonica A
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2017
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vol. 131
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issue 4
863-865
EN
Functionalized multiwall carbon nanotubes as well as nanocomposite based on that material covered by nanoparticles composed of iron oxides were the subject of investigations. In order to identify all iron-bearing phases including those reported on the base of previous X-ray diffraction measurements, the transmission Mössbauer spectroscopy was utilized. The experiments were carried out both at room temperature and also at low temperatures. It was stated that in the investigated nanotubes some impurities were present, originating from the catalyst remains, in form of Fe-C and α -Fe nanoparticles. The Mössbauer spectra collected for the nanocomposite showed a complex shape characteristic of temperature relaxations. The following subspectra related to iron-based phases were identified: sextet attributed to hematite, with hyperfine magnetic field reduced due to the temperature relaxations, sextet corresponding to iron carbide as well as two doublets linked to superparamagnetic hematite and ferrihydrites.
15
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.
16
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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