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1
Content available remote

Puzzling Magnetism of Gd_3Cu_4Sn_4

100%
Łątka K., Pacyna A., Pöttgen R., Schappacher F.
Acta Physica Polonica A
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2008
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vol. 114
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issue 6
1501-1508
EN
A polycrystalline, single phase sample of Gd_3Cu_4Sn_4 (Gd_3Cu_4Ge_4 type, Immm, a = 1473.5(1), b = 694.1(1), c = 447.2(1) pm) was synthesized by arc-melting of the elements and subsequent annealing of the sample at 1220 and 970 K, respectively. The magnetic properties of this compound were studied thoroughly by AC and DC magnetic susceptibility measurements and ^{155}Gd Mössbauer spectroscopy. These results reveal two antiferromagnetic phase transitions close to 13 and 8.6 K, respectively. The thermal variation of the magnetic hyperfine fields observed at two inequivalent Gd sites point to two magnetic substructures, which order independently.
2
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Kinetic Exchange in Diluted Magnetic Semiconductors of Wurtzite Structure

100%
Blinowski J., Kacman P.
Acta Physica Polonica A
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1993
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vol. 84
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issue 4
693-696
EN
Kinetic exchange between valence electrons and paramagnetic ions in diluted magnetic semiconductors of wurtzite structure is examined and compared with the results obtained previously for zinc-blende type diluted magnetic semiconductors. Two limiting electron configurations of the impurity ion, d^{5} and d^{1}, are discussed. For the former, it is shown that the exchange constant anisotropy, experimentally observed in CdMnSe, results from the anisotropy of the hybridization matrix elements. In the latter case, apart from the similar anisotropy of the ferromagnetic exchange constant, additional, antiferromagnetic corrections should be expected, since for this particular symmetry the hybridization between the ground state of the ion and valence band becomes allowed.
3
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Mechanism of Rotational Hysteresis Energy in Sm-Fe-N Permanent Magnets

100%
Pawlik P., Wysłocki J., Dziliński K.
Acta Physica Polonica A
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2002
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vol. 101
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issue 2
267-277
EN
Investigations were carried out on Sm-Fe-N permanent magnet produced by the reactive diffusion method with different grain sizes (from 8.6 to 0.97μm). The rotational hysteresis energy has been measured as a function of the applied field. The proposed model of rotational hysteresis energy is in good agreement with the experimental results. It is shown that the magnetization reversal process in Sm-Fe-N magnet is controlled by the nucleation of reversed domains.
4
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Influence of Hydrostatic Pressure on Magnetic Properties of (Sr,La)(Ru,Cr,Mn)O_3

100%
Piętosa J., Wiśniewski A., Puźniak R., Kolesnik S., Majjiga M., Dabrowski B.
Acta Physica Polonica A
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2007
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vol. 111
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issue 1
159-163
EN
An influence of hydrostatic pressure, P, on phase transition temperature, T_C, and spontaneous magnetisation, M_0, of selected perovskite ruthenates (SrRuO_3, La_{0.2}Sr_{0.8}RuO_3, SrRu_{0.9}Mn_{0.1}O_3, and SrRu_{0.9}Cr_{0.1}O_3) was determined to 12 kbar. A decrease in T_C with pressure was found for all of the studied samples. The M_0(P) remains unchanged for most of the samples, except for the La_{0.2}Sr_{0.8}RuO_3 sample. The weakening of ferromagnetic interactions with increasing pressure is consistent with complex band structure effects related to the modulation of the Ru-O hybridisation by the change of structural distortion.
5
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Effect of Post Annealing on La_{0.7}Sr_{0.3}MnO_3 Thin Films

100%
Cheng W., Leung C.
Acta Physica Polonica A
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2007
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vol. 111
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issue 1
117-122
EN
The stability of La_{0.7}Sr_{0.3}MnO_3 thin films fabricated by pulsed laser deposition, under different annealing procedures, was investigated. La_{0.7}Sr_{0.3}MnO_3 films were deposited on (100) LaAlO_3 substrates at 650ºC with the films thickness from 20 to 50 nm. The oxygen pressures used to fabricate the films were 150 mTorr and 100 mTorr. Then in situ annealing steps were performed at 100 and 150 mTorr, respectively. Curie temperatures (T_c) of the films were estimated from the peaks of the temperature dependent resistance data. For the films deposited at 100 mTorr and annealed at 150 mTorr, T_c slightly dropped for short annealing time and recovered to 360 K for 30 min annealing. For the films deposited at 100 mTorr and annealed at 150 mTorr, it maintained semiconducting behavior without transition after annealing up to 30 minutes. For ex situ post annealing, it was found that the T_c of the films strongly depended on the annealing procedures.
6
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Magnetic Properties of Ni_{0.3}Zn_{0.7}Fe₂O₄ Ferrites with Iron Ions Partly Substituted by Europium

100%
Ušák E., Ušáková M., Šoka M., Vašut D.
Acta Physica Polonica A
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2017
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vol. 131
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issue 4
717-719
EN
This work is devoted to the study of the impact of the substitution of iron by Eu on the properties of magnetically soft Ni_{0.3}Zn_{0.7}Eu_{x}Fe_{2-x}O_4 ferrites aimed at enhancement of the knowledge related to the behavior of such materials in dependence on the amount of iron substitution. Our latest studies focused on the materials having similar chemical composition gave a hint of some possible approaches to manage the resulting magnetic properties in a precisely controlled way by the combination of several factors; choice of initial chemical composition of non-substituted ferrite, selection of substituted and substituting element, variations of final chemical composition, modifications of fabrication technology (sintering temperature and time), etc.
7
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The Influence of Compressive Stresses on the Properties of Inductive Electronics Components

100%
Salach J., Nowak P.
Acta Physica Polonica A
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2018
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vol. 133
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issue 4
1053-1055
EN
This paper presents results of investigation of stress influence on magnetic characteristics of ferrite ring cores for inductive electronics components. Ring-shaped cores were made of Ni-Zn ferrite designed for anti-lung filter cores. The results of the study indicate a significant impact of external forces stresses on the magnetic properties of ferrite cores. Such changes are very important due to their influence on the correct operation of the induction components.
8
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Magnetic Anisotropy of Lu_2Co_{17-x}Si_x Single Crystals

100%
Tereshina E., Andreev A., Šantavá E., Daniš S.
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EN
Magnetic anisotropy of Lu_2Co_{17-x}Si_x single crystals grown by the Czochralski method was investigated. The homogeneity range of Si substitution for Co extends up to x = 3.4 in Lu_2Co_{17-x}Si_x solid solutions. The unit cell volume, Curie temperature, and spontaneous magnetic moment decrease monotonously with increasing Si content. Lu_2Co_{17} has the easy-plane type of magnetic anisotropy in the ground state, which changes into the easy-axis type by two spin-reorientation transitions of the second-order, the easy-plane-easy-cone at T_{SR1}~680 K and the easy-cone - easy-axis at T_{SR2}~730 K. Upon Si substitution, the observed spin-reorientations shift towards the lower temperatures for Lu_2Co_{17-x}Si_x (T_{SR1}~75 K and T_{SR2}~130 K in Lu_2Co_{16}Si) and vanish for compounds with 1
9
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Neutron Diffraction Studies of MnFeAs_{y}P_{1-y} System

100%
Zach R., Bacmann M., Fruchart D., Soubeyroux J., Nizioł S., Fruchart R.
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EN
Magnetic structures of the MnFeAs_{y}P_{1-y} system were examined by means of the neutron diffraction technique in the 1.5-300 K temperature range. Atomic ordering in the metal sublattices, temperature dependence of the incommensurate (y = 0.2 and y = 0.275) and of the ferromagnetic (y = 0.275, y = 0.3, y = 0.5) ordering is discussed.
10
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Magnetic Phase Transitions in TbNi(Al,In) Compounds

100%
Klicpera M., Javorský P., Šantavá E.
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issue 5
881-883
EN
The magnetic phase transitions in TbNiAl_{1-x}In_{x} compounds were investigated by ac-susceptibility measurements. Our data reveal magnetic ordering with transition temperatures between 40 and 70 K, depending on the In concentration. All the studied compounds exhibit two or more phase transitions accompanied by distinct anomalies in the real and imaginary part of the ac-susceptibility. The paramagnetic Curie temperatures remain positive in the whole series.
11
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Pressure Influence on Magnetic Properties of TbNiAl

100%
Javorský P., Prchal J., Klicpera M., Kaštil J., Míšek M.
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vol. 126
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issue 1
280-281
EN
We have investigated the effect of hydrostatic pressure on magnetic properties of TbNiAl, crystallizing in hexagonal ZrNiAl-type structure. TbNiAl orders antiferromagnetically below T_{N}=45 K and undergoes further magnetic phase transition to another AF phase at T_{1}=23 K. The magnetic field of B_{c} ≅ 0.3 T applied along the c-axis at 2 K leads to the transition to ferromagnetic order. By applying the hydrostatic pressure, both T_{N} and T_{1} remain almost unaffected whereas B_{c} shows a strong increase. The hydrostatic pressure stabilizes the antiferromagnetic state which can be related to development of structural parameters.
12
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X-MCD Study of Expanded Lattice Permanent Magnet Materials

100%
Kapusta C., Mycielski R., Porębska B., Ahlers D., Attenkofer K., Fischer P., Schütz G.
Acta Physica Polonica A
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1997
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vol. 91
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issue 5
975-979
EN
X-ray magnetic circular dichroism measurements on the cobalt (iron) K edges and samarium L_{2}, L_{3} edges of Sm_{2}Fe_{17}, Sm_{2}Co_{17} and their interstitial hydrides and nitrides are reported. Normal absorption profiles show considerable changes upon nitriding for iron- and cobalt K edge and for samarium L_{2}, L_{3} edges. Much weaker changes are observed upon hydriding. Similarly, significant differences of X-MCD spectra appear between the host Sm_{2}Fe_{17} (Sm_{2}Co_{17}) and the nitrides, whereas X-MCD signals of the hydrides are similar to those of the hosts. The effects are analysed and discussed in terms of influence of interstitial atom neighbours on the Co(Fe) 4p and Sm 5d electronic bands.
13
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Superexchange in A^{II}B^{VI} Diluted Magnetic Semiconductors with Mn, Fe and Co Ions

100%
Blinowski J., Kacman P.
Acta Physica Polonica A
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1995
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vol. 87
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issue 2
539-542
EN
A theory of superexchange, the dominant ion-ion spin interaction, for Mn-, Fe- and Co-based DMS is presented. The theory takes into account the band structure of A^{II}B^{VI} compounds, the orbital dependence of the hybridization and the intra shell correlations of the d-electrons, which are essential in the case of the non-S-state ions. The general formulae relating the superexchange to the band structure and the ionic energy spectrum were obtained - the dominant part of the superexchange turns out to be inversely proportional to the square of the ionic spin. This explains the observed in­crease in the average values of d-d exchange constants, when passing from Mn via Fe to Co ions in DMS.
14
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Temperature Resistance of Magnetoelastic Characteristics of 13CrMo4-5 Constructional Steel

80%
Jackiewicz D., Kachniarz M., Rozniatowski K., Dworecka J., Szewczyk R., Salach J., Bienkowski A., Winiarski W.
Acta Physica Polonica A
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2015
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vol. 127
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issue 2
614-616
EN
In the paper the results of investigation on tensile stresses dependence of magnetoelastic characteristics of cores made of 13CrMo4-5 constructional steel are presented. In the investigation step-cooling test treated samples were used. The step-cooling test process is a type of heat treatment simulating effects of passing time and environmental conditions (temperature and stress) on the sample. In the paper the method of testing the influence of stresses on the magnetic characteristics is presented. Frame shaped samples ensured a closed magnetic circuit and homogeneous distribution of stress. It was found that step-cooling test does not significantly influence the magnetoelastic characteristics and the structure of the samples. On the other hand, then tensile stresses significantly change the magnetic characteristics of 13CrMo4-5 constructional steel. That confirms the possibility of using measurements based on the magnetoelastic effect in the stress assessment for industrial non destructing testing of steel constructions.
15
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Characterization of New U-Ni-X₂ Splats and Study of their Physical Properties

80%
Molčanová Z., Mihalik M., Mihalik M., Reiffers M., Džubinská A., Huráková M., Kavečanský V., Paukov M., Havela L.
Acta Physica Polonica A
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2017
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vol. 131
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issue 4
994-996
EN
We explored the crystal structure, magnetic, and transport properties of UNiX₂ (X = Ge, Si) materials, which were prepared by a conventional metallurgical technique and by rapid solidification - splat cooling. The UNiSi₂ splat is mostly single phase, containing only small traces of a minority phase. Magnetic and electrical properties of the splat resemble properties of samples, which were prepared by conventional methods, exhibiting a ferromagnetic transition at about 91 K and similar temperature dependence of resistivity. The coercive field of μ₀H_c=4.25 T is much enhanced due to the magnetic anisotropy introduced by the sample preparation technique. The Barkhausen jumps were observed on the hysteresis loop. Magnetization of the sample does not saturate in fields up to μ₀H=9 T. The phase structure of UNiGe₂ splat is not completely solved and will be subject of our study in future. Our preliminary results indicate the presence of completely new phase with tetragonal crystal structure and antiferromagnetic ordering below 54 K.
16
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Magnetic and Heat Capacity Study of the new Gd_{1-x}Ce_xNi₅ Series

80%
Dzubinska A., Reiffers M., Espeso J., Rodríguez Fernández J.
Acta Physica Polonica A
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2017
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vol. 131
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issue 4
997-999
EN
We have prepared a new system of Gd_{1-x}Ce_xNi₅ polycrystalline samples with concentrations x =0, 0.2, 0.5, and 0.8 in order to study the influence of different rare-earths substitutions on the ground state connected with spin fluctuations. GdNi₅ is a ferromagnetic compound with T_{C}=31.8 K and CeNi₅ is a well-known spin fluctuation compound without magnetic ordering down to the lowest temperatures. X-ray diffraction study confirms the hexagonal crystal structure and the single phase samples. Magnetic properties (M(T),M(B)) show that an increasing content of Ce depresses the transition temperature, T_{C}, down to 4.9 K for x=0.8. The heat capacity measurements confirmed these results.
17
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Solution and Refinement of Magnetic Structures with Jana2006

80%
Petříček V., Henriques M., Dušek M.
Acta Physica Polonica A
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2016
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vol. 130
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issue 4
848-851
EN
The program Jana2006 allows the solution and refinement of regular, twinned, modulated, and composite structures against different diffraction data sets. Recently a new option for solving and refining magnetic structures from powder and single crystal neutron diffraction data has been developed.
18
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Crystal Structure and Magnetic Properties of new Eu-Pd-Sn Compounds

80%
Čurlík I., Gastaldo F., Giovannini M., Strydom A., Reiffers M.
Acta Physica Polonica A
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2017
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vol. 131
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issue 4
1003-1005
EN
We report on the synthesis, crystal structure determination, and magnetic susceptibility measurements of Eu₃Pd₂Sn₂, EuPd₂Sn₄, and EuPdSn₂. For all three compounds a divalent state of Eu ions was obtained from the fitting of the magnetic susceptibilities. At low temperatures Eu₃Pd₂Sn₂, EuPd₂Sn₄, and EuPdSn₂ order magnetically at 23, 12, and 13 K, respectively.
19
Content available remote

Grazing Incidence X-Ray Reflectivity Study of MBE-Grown Co/Cu Multilayers

80%
Pełka J. B., Baczewski L. T., Wawro A., Domagała J.
Acta Physica Polonica A
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1997
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vol. 91
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issue 5
859-863
EN
In this work we report preliminary grazing-incidence X-ray reflectometry studies of multilayer structures composed of 3d metals Co and Cu deposited in the ultra-high vacuum molecular beam epitaxy system. The multilayers of different modulation period were deposited on glass substrate directly, or on 3d -metallic buffers of various thicknesses. The experimental specular reflectivity spectra were analyzed by a comparison with a theoretical model calculated from a recursive algorithm based on the Fresnel formula [1, 2]. It enabled us to estimate the structural parameters concerning layer thickness and roughness. The results obtained are correlated with magnetization measurements of the layered structures, as a function of modulation period, buffer type and thickness. A special attention to influence of interfacial roughness on magnetization results is paid.
20
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Electrical Transport and Magnetic Properties of La_{2/3}Pb_{1/3}MnO_3 Thin Films

80%
Baran M., Berkowski M., Fink-Finowicki J., Lewandowski S., Szymczak H., Szymczak R., Khartchev S., Medvedev Y.
Acta Physica Polonica A
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2004
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vol. 105
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issue 1-2
115-120
EN
The magnetic and transport properties of epitaxial La_{2/3}Pb_{1/3}CuO_3 thin films deposited on SrLaGaO_4 substrate using dc magnetron sputtering technique are reported. The giant magnetoresistance effect (of about 50% at magnetic field of 1 T) was observed near the Curie temperature. Several mechanisms responsible for temperature dependence of resistivity are discussed. The effect of annealing was studied. It shifted the Curie temperature to the lower value, probably, because of the loss of oxygen.
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