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1
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Ferromagnetic Resonance in Very Fine Co Particles forming Granular Co-Cu Films

100%
Dubowik J., Kudryavtsev Y. V.
Acta Physica Polonica A
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1997
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vol. 91
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issue 2
249-252
EN
Ferromagnetic resonance was investigated in heterogeneous Co-Cu thin films consisting of randomly oriented fine Co particles embedded in Cu matrix. The experimental spectra are modelled using dynamic susceptibility approach assuming a broad distribution in particle sizes and dipolar interactions between particles.
2
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Ferromagnetic Resonance in Fe/Zr Multilayers

100%
Dubowik J., Stobiecki F.
Acta Physica Polonica A
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1994
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vol. 85
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issue 2
449-453
EN
We report our ferromagnetic resonance measurements for three series of Fe/Zr multilayers with thickness ratio of Fe to Zr sublayers equal to 2:1, 1:1, and 1:2, respectively. These measurements may serve as an example of employing ferromagnetic resonance technique as a sensitive probe for monitoring the magnetic phases formed at interfaces in the earliest stages of the interdiffusion reaction in multilayer Fe/Zr films for which the onset of the amorphization takes place during deposition due to thermodynamics of the system. The resulting structure may be regarded as strongly inhomogeneous one that includes distinct ferromagnetic phases related to the Fe atoms in various surroundings.
3
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Magnetic Studies of Polycrystalline Magnetostrictive CoPd Films with Large Planar Strain

100%
Dubowik J., Szymański B.
Acta Physica Polonica A
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1994
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vol. 85
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issue 5
863-867
EN
We report on ferromagnetic resonance and torque curves measurements in electrodeposited CoPd alloy films with composition ranged from Co_{13}Pd_{87} to Co_{45}Pd_{55}. We show that the origin of the multimode structure of ferromagnetic resonance spectra in these strongly magnetostrictive polycrystalline films can be satisfactorily explained on the basis of the independent-grain-approach for a textured microstructure. The fourfold periodicity of the torque curves for the compositional range of 30-35 at% of Co seems to be originated by the microstructure features which lead to a distribution of the easy axis directions within the films.
4
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Inverse Spin Hall Effect by Spin-Pumping in Co_2Cr_{0.4}Fe_{0.6}Al/Pt Structures

100%
Gościańska I., Dubowik J.
Acta Physica Polonica A
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2010
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vol. 118
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issue 5
851-853
EN
Inverse spin Hall effect consists in conversion of spin currents into electric currents and has recently been observed using spin-pumping operated by ferromagnetic resonance in permalloy/Pt(Cr) thin film structures. We prepared several Co_2Cr_{0.4}Fe_{0.6}Al/Pt thin film structures to observe for the first time inverse spin Hall effect in bilayer structures comprising ferromagnetic half-metallic Heusler alloy. In but a few Co_2Cr_{0.4}Fe_{0.6}Al/Pt samples we succeeded in observing inverse spin Hall effect voltage of few microvolts by spin pumping resulting from ferromagnetic resonance. This confirms that spin polarized current can be transferred into Pt layer. Inverse spin Hall effect was 2-3 times larger than that detected in permalloy/Pt bilayer under the same conditions.
5
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Micromagnetic Approach to Exchange Bias

100%
Dubowik J., Gościańska I.
Acta Physica Polonica A
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2015
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vol. 127
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issue 2
147-152
EN
We present a micromagnetic approach to the exchange bias in ferromagnetic/antiferromagnetic thin film systems with a small number of irreversible interfacial magnetic moments. We express the exchange bias field H_{EB} in terms of the fundamental micromagnetic length scale of ferromagnetic - the exchange length l_{ex}. The benefit from this approach is a better separation of the factor related to the ferromagnetic layer from the factor related to the ferromagnetic/antiferromagnetic coupling at interfaces. Using this approach we estimate the upper limit of H_{EB} in real ferromagnetic/antiferromagnetic systems.
6
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Ferromagnetic Resonance in Metallic Thin Films and Thin-Film Tubes

100%
Dubowik J., Gościańska I.
Acta Physica Polonica A
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2008
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vol. 113
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issue 1
179-182
EN
A model describing ferromagnetic resonance in thin-film magnetic metallic tubes is proposed and compared with the experimental ferromagnetic resonance spectra of the thin-film Ni.
7
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Superparamagnetic Grains as Source of Giant Magnetoresistance Effect in Discontinuous Co/Ag Multilayers

81%
Luciński T., Stobiecki F., Dubowik J., Czajka R.
Acta Physica Polonica A
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1997
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vol. 91
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issue 2
269-272
EN
The as-deposited and annealed Co/Ag discontinuous multilayer-like structures were examined. Discontinuous Co sublayers are thought to consist of fine superparamagnetic and ferromagnetic grains. Using the bimodal superparamagnetic grain sizes distribution the GMR(H) dependencies were successfully modelled with the use of two Langevin functions simulating the magnetization of the superparamagnetic grains.
8
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Exchange Coupled NiFe/NiMn Bilayer Studied by a Vector Network Analyzer Ferromagnetic Resonance

81%
Głowiński H., Załęski K., Sprada J., Dubowik J.
Acta Physica Polonica A
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2012
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vol. 121
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issue 5-6
1145-1147
EN
Using cavity ferromagnetic resonance and vector network analyzer ferromagnetic resonance unidirectional, uniaxial and rotatable anisotropies were determined in permalloy(30 nm)/NiMn(56 nm). Resonance field dependence on in-plane angle clearly shows unidirectional and uniaxial anisotropy. Rotatable anisotropy, which acts as internal magnetic field independent of a direction of external magnetic field, is observed on vector network analyzer ferromagnetic resonance as upward shift of the resonance frequency of Py/NiMn compared to Py film. Even for a small exchange bias field, this shift is significantly large.
9
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Temperature Dependence of Magnetization Damping in Heusler Alloy Films

81%
Dubowik J., Załęski M., Głowiński H., Gościańska I.
Acta Physica Polonica A
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2010
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vol. 118
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issue 5
848-850
EN
The Gilbert damping for Co_2CrAl (Co_2Cr_{0.3}Fe_{0.7}Al) and Ni_2MnSn Heusler alloy films was investigated as a function of temperature. The best films reveals the Gilbert damping nearly independent of temperature. Magnetic relaxation in Co_2CrAl is strongly influenced by magnetic inhomogeneities due to phase separation. The best Ni_2MnSn epitaxial films have comparable Gilbert damping α of 6× 10^{-3} as half-metallic Co_2Cr_{0.3}Fe_{0.7}Al films with α = 3 × 10^{-3}.
10
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Martensitic Transformations and Magnetic Properties of Ni-Mn-Sn Heusler Alloy Films

81%
Dubowik J., Szlaferek A., Gościańska I.
Acta Physica Polonica A
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2008
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vol. 113
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issue 1
163-168
EN
We report on structural and magnetic properties of Ni_{50}Mn_{50-x}Sn_x (x=12÷14) films and compare them with those of the bulk Ni-Mn-Sn alloys. Magnetic measurements reveal clear presence of martensitic transformation in bulk alloys but in the flash-evaporated Ni-Mn-Sn thin films martensitic transformation is usually less visible. The best film samples annealed for 1 h at about 900 K exhibit clear signs of martensitic transformation: i.e., a small defect in magnetization and a substantial increase in ferromagnetic resonance line width.
11
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Electronic Structure and Magnetic Properties of Ni_2MnGa_{1-x}Ge_{x} and Disordered Ni_{2}MnSn Heusler Alloys

81%
Pugaczowa-Michalska M., Jezierski A., Dubowik J., Kaczkowski J.
Acta Physica Polonica A
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2009
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vol. 115
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issue 1
241-243
EN
In this work we present the influence of atomic disorder on the electronic and magnetic properties of Ni_{2}MnGa_{1-x}Ge_{x} and Ni_{2}MnSn Heusler alloys. Ab initio band calculations were performed for the experimental lattice parameters. We applied SPR-KKR-CPA methods in the local spin density approximation.
12
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Electric and Magnetic Signatures of Structural and Chemical Ordering of Heusler Alloy Films

71%
Dubowik J., Gościańska I., Załęski K., Kudryavtsev Y., Lee Y.
Acta Physica Polonica A
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2009
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vol. 115
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issue 1
360-362
EN
We present results of in situ temperature measurements of resistivity for some amorphous or partially crystalline Heusler alloy films: Co_{2}CrAl, Co_{2}MnGa and off-stoichiometric Ni_{2}Mn_{1+x}Sn_{x}, Ni_{2}Mn_{1-x}Ga_{x} that are known to exhibit half-metallic properties and martensitic transformations, respectively. From ρ vs. T characteristics we distinguish various stages of chemical and structural ordering in the films. They appear to be quite distinct in both systems investigated. The resistivity results are compared with magnetic characteristics for Co_{2}MnGa with a high Curie temperature.
13
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Anisotropy Distribution in NiFe/Au/Co/Au Multilayers

71%
Dubowik J., Stobiecki F., Gościańska I., Kociemba M., Bednarski W.
Acta Physica Polonica A
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2009
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vol. 115
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issue 1
315-318
EN
We present results of FMR investigations of anisotropy distribution in uncoupled [NiFe/Au/Co/Au]_N structures with alternating in-plane (NiFe) and out-of-plane anisotropies (Co). It is concluded that for NiFe layers anisotropy distribution is negligible and can be increased by "dusting" of NiFe with ultrathin Co layers. The perpendicular anisotropy K_{U}^2 of Co layers depends on Co thickness in a standard way ∝ 1/d_{Co}, and is distributed in a range of ≈10-20% of K_{U}^2 (i.e., ≈ 1.5× 10^6 erg/cm^3).
14
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Determination of Exchange and Rotatable Anisotropies in Co₂FeSi/IrMn Exchange Coupled Structures using Broadband Ferromagnetic Resonance

71%
Głowiński H., Schmidt M., Krysztofik A., Gościańska I., Dubowik J.
Acta Physica Polonica A
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2015
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vol. 127
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issue 2
531-533
EN
We determined exchange H_{ex} and rotatable H_{rot} anisotropy fields of multilayers that comprise 10 nm Co₂FeSi (CFS) layers exchange coupled to 20 nm IrMn layers by using ferromagnetic resonance with a vector network analyzer (VNA-FMR). The multilayer structures consist of IrMn/bottom (b)-CFS/IrMn/middle (m)-CFS/IrMn/top (t)-CFS/IrMn layers so that each CFS layer is surrounded by a pair of IrMn layers. In the structures, the exchange bias field propagates in such a way that H_{ex}^{t} > H_{ex}^{m} > H_{ex}^{b} for the top, middle, and bottom layer, respectively. FMR response measured along the exchange bias (EB) axis consist of only two absorptions related to the (b+m)- and (t)-CFS layers, respectively. Exchange and rotatable anisotropy determined independently from angular and dispersion measurements of the resonance fields are nearly the same. Rotatable anisotropy field scales with the exchange bias field in these complex structures.
15
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Ultrafast Magnetization Dynamics in Epitaxial Ni-Mn-Sn Heusler Alloy Film

71%
Bonda A., Uba S., Załęski K., Dubowik J., Uba L.
Acta Physica Polonica A
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2018
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vol. 133
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issue 3
501-504
EN
The work is devoted to studies of ultrafast magnetization dynamics induced by femtosecond laser pulses in ferromagnetic Ni-Mn-Sn shape memory Heusler alloy. We studied epitaxial thin Ni_{54.3}Mn_{31.9}Sn_{13.8} film deposited on (001) MgO substrate. Spin precession in an external magnetic field was triggered and detected by the time-resolved magneto-optical Kerr effect (TRMOKE) using pump-probe technique in dual color scheme experiment. Measurements were performed as a function of magnetic field H and pulse power P. The measured TRMOKE signal is composed of oscillatory and background components, both decaying exponentially in a nanosecond time scale. The precession frequency was determined and found to be varying in the range of 1-10 GHz with H up to 3 kOe and decreasing linearly with P. The dependence of Gilbert damping parameter α on H was determined and discussed.
16
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Exchange Bias in Ni-Mn-Sn Heusler Alloy Films

71%
Gościańska I., Załęski K., Głowiński H., Kudryavtsev Y., Dubowik J.
Acta Physica Polonica A
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2012
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vol. 121
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issue 5-6
1179-1181
EN
We report a relatively large exchange bias effect observed for the first time in Ni-Mn-Sn thin films with different microstructure and composition: a Ni_{50}Mn_{36}Sn_{14} epitaxial film (A), a Ni_{50}Mn_{43}Sn_7 film which is phase decomposed (B), and a NiMn/Ni_{50}Mn_{25}Sn_{25} bilayer (C). Despite the samples differ markedly in both microstructure and composition H_{EB} does not substantially differs at 5 K. Exchange bias decreases with increasing T approximately as H_{EB} (T) ∝ H_{EB} (5K)/T with H_{EB} (5K) of 180 Oe and 60 Oe for sample B and C, respectively and almost linearly for sample A with H_{EB} (5K) = 65 Oe. Blocking temperature where the exchange bias vanishes is 40, 50 and 80 K for sample A, C and B, respectively. The results suggest that the role of AFM/FM interfaces is not substantial in formation of exchange bias in Ni-Mn-Sn Heusler alloy films and exchange bias is rather related to AFM/FM interactions in nanoscale.
17
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High-Quality Ni-Fe/Cu Multilayer Films with Antiferromagnetic Coupling

62%
Stobiecki F., Dubowik J., Luciński T., Szymański B., Rohrmann H., Röll K., Schmidt M.
Acta Physica Polonica A
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1997
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vol. 91
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issue 2
277-280
EN
We report structural and magnetic properties of Ni_{83}Fe_{17}/Cu multilayer films with various buffer layer and sublayer thicknesses of copper d_{Cu} and Permalloy d_{Py} deposited by face-to-face sputtering. The following features prove a good quality of our films: a well-layered structure, complete antiferromagnetic coupling with a low coupling strength (2×10^{-5} J/m^{2} for d_{Cu}=1 nm and 10^{-6} J/m^{^2} for d_{Cu}=2.1 nm) and a low coercive field which make them attractive for possible applications as giant magnetoresistance sensors.
18
Content available remote

Complex Magnetic Structure of Strongly Coupled Fe/Si Multilayers

62%
Dubowik J., Stobiecki F., Szymański B., Kudryavtsev Y., Grabias A., Kopcewicz M.
Acta Physica Polonica A
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2000
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vol. 97
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issue 3
451-454
EN
Fe/Si multilayers with strong bilinear and biquadratic couplings were investigated. A complex structure revealed by the Mössbauer spectroscopy corresponds to multimode ferromagnetic resonance spectra in a non-saturated state. Simple dispersion relations for antiferromagnetic coupled bilayer structures are shown to be inapplicable to the Fe/Si multilayers with a strong biquadratic component to the antiferromagnetic bilinear coupling.
19
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Epitaxial Growths and Magnetization Dynamics of Ni_{2}MnSn Heusler Alloy Films

62%
Dubowik J., Gościańska I., Załęski K., Głowiński H., Ehresmann A., Kakazei G., Bunyaev S.
Acta Physica Polonica A
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2012
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vol. 121
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issue 5-6
1121-1123
EN
Ferromagnetic resonance has been investigated in Ni_{2}MnSn Heusler alloy films. The films were deposited at 673
20
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He⁺ Ion Bombardment Induced Effects on Magnetic Properties of Ni-Fe/Au/Co/Au Films

52%
Kuświk P., Szymański B., Urbaniak M., Dubowik J., Stobiecki F., Kisielewski J., Tekielak M., Maziewski A., Weis T., Ehresmann A.
Acta Physica Polonica A
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2008
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vol. 113
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issue 2
651-656
EN
The influence of He⁺ (10 keV) ion bombardment on magnetic properties of sputter deposited Ni_{80}Fe_{20}/Au/Co/Au layered films was studied. The variable parameters were the thickness of the Co layer or Au spacer and the ion dose. The magnetooptical Kerr measurements were performed on samples with wedge shaped Co or Au layers. With increasing dose of helium ions the following changes in magnetic properties were observed: (i) a decrease in the Co thickness range corresponding to the perpendicular anisotropy, (ii) a decrease in the coercive field (H_C), (iii) an increase in the ferromagnetic coupling between ferromagnetic layers.
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