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1
Publication available in full text mode
Content available

Effect of Post Annealing on La_{0.7}Sr_{0.3}MnO_3 Thin Films

100%
Cheng W., Leung C.
Acta Physica Polonica A
|
2007
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vol. 111
|
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.
2
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Kinetic Exchange in Diluted Magnetic Semiconductors of Wurtzite Structure

100%
Blinowski J., Kacman P.
Acta Physica Polonica A
|
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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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.
4
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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.
5
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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.
6
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Magnetic Anisotropy of Lu_2Co_{17-x}Si_x Single Crystals

100%
Tereshina E., Andreev A., Šantavá E., Daniš S.
Acta Physica Polonica A
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2008
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vol. 113
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issue 1
235-238
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
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
|
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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Neutron Diffraction Studies of MnFeAs_{y}P_{1-y} System

100%
Zach R., Bacmann M., Fruchart D., Soubeyroux J., Nizioł S., Fruchart R.
Acta Physica Polonica A
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1994
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vol. 85
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issue 1
229-231
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.
9
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Pressure Influence on Magnetic Properties of TbNiAl

100%
Javorský P., Prchal J., Klicpera M., Kaštil J., Míšek M.
Acta Physica Polonica A
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2014
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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.
10
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Magnetic Phase Transitions in TbNi(Al,In) Compounds

100%
Klicpera M., Javorský P., Šantavá E.
Acta Physica Polonica A
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2010
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vol. 118
|
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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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.
12
Publication available in full text mode
Content available

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.
13
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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.
14
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Point Contact Properties of R_3Pd_{20}X_6 (R = La, Ce; X = Si, Ge) Cage Compounds

80%
Čurlik I., Strydom A., Reiffers M.
Acta Physica Polonica A
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2010
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vol. 118
|
issue 5
907-909
EN
Point-contact spectroscopy measurements have been performed on the R_3Pd_{20}X_6 (R = La, Ce; X = Si, Ge) cage compounds. In case of La the characteristic phonon energies have been obtained in agreement with that of the Raman scattering. In Ce_3Pd_{20}Si_6 we have observed asymmetric behaviour of dV/dI(V) dependences which was observed in non-Fermi liquid compound. In Ce_3Pd_{20}Ge_6 we have observed maxima at crystalline electric field energies, influenced by magnetic field. This is connected with quadrupolar ordering transition.
15
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Strong Electronic Correlations in a New Yb-Based Compound: YbCu_4Ni

80%
Čurlik I., Reiffers M., Giovannini M., Gažo E., Šebek J., Šantavá E.
Acta Physica Polonica A
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2010
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vol. 118
|
issue 5
919-921
EN
Heat capacity measurements performed on the new ternary compound YbCu_4Ni indicate for this compound strong electronic correlations with possible antiferromagnetic phase transition below 0.5 K. Susceptibility and magnetisation measurements above 2 K show no magnetic ordering.
16
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Magnetic Stray Field Detection as Guidance for Electronic Transport Measurements in the B-T Phase Diagram of MnSi

80%
Pohlit M., Witt S., Akbari M., Krellner C., Müller J.
Acta Physica Polonica A
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2018
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vol. 133
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issue 3
582-584
EN
In order to advance modern information technologies, progress in both the fabrication of magnetic nanostructures and of complex materials, from which small magnetic entities - like the skyrmions present in MnSi - emerge and in developing measurement techniques are desired. Here the sensor-based stray field detection using tailor-made micro-Hall magnetometers has proven to be a versatile tool for studying the magnetization reversal of individual magnetic nanostructures, domain wall motion in thin films, as well as the local stray field close to macroscopic samples. In this article we demonstrate that the local stray field can be used to accurately map out the B-T phase diagram of MnSi and serve as a guidance for simultaneously-performed electronic transport measurements. The presented study also serves as a proof-of-principle experiment for future combined investigations of electronic transport and magnetization focusing on electrically-contacted magnetic nanostructures.
17
Publication available in full text mode
Content available

Local Magnetic and Electronic Properties of the A2FeM'O6 (A = Ba, Sr, Ca, M' = Mo, Re) Double Perovskites

80%
Zając D., Sikora M., Prochazka V., Borowiec M., Stępień J., Kapusta C., Riedi P., Marquina C., De Teresa J., Ibarra M.
Acta Physica Polonica A
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2007
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vol. 111
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issue 6
797-820
EN
The results of a combined NMR, X-ray absorption spectroscopy and X-ray magnetic cirrcular dichroism study of the AA'FeMoO_6 and AA'FeReO_6 double perovskites are presented. They revealed a dependence of electronic and magnetic properties, including a d-electron transfer between Fe and Mo sites, on the structural tolerance factor. The maximum value of the 4d Mo electron occupation and the corresponding Mo moment is obtained for the tolerance factor of unity. This corresponds to the maximum strength of the magnetic interaction and, respectively, to the Curie temperature. The dominant T^{5/2} type temperature dependence of the Mo hyperfine field reveals the half-metallicity of the AA'FeMoO_6 compounds. Antisite defects and antiphase boundaries have been identified in NMR measurements and the strength of their magnetic coupling have been determined. A considerable orbital contribution to the Re and Fe magnetic moments were found in the NMR and X-MCD measurements on the AA'FeReO_6 compounds. Its magnitude decreases with increasing structural tolerance factor and is correlated with their magnetic anisotropy.
18
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Ageing Phenomena in La-Sr Manganites with Divalent Substituents for Manganese

80%
Merkulov D., Badelin A., Estemirova S., Karpasyuk V.
Acta Physica Polonica A
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2018
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vol. 133
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issue 3
529-531
EN
Variations of electromagnetic and structural characteristics of La_{1-c+x}Sr_{c-x}Mn_{1-x}Me_{x}O_{3+γ} manganites (Me = Zn, Ni) during storage time up to 36000 hours at room temperature and after frequentative thermal cycling in the 300-573 K range were investigated. Changes of magnetization of all samples were within the error of measurement. In most cases Curie point (T_{C}) showed irregular variations within the range of 20%, while zinc-substituted manganites with relatively high values of "c" exhibited some trend of T_{C} rise. The resistance of all samples increased during storage period. The cell volume of single-phase manganites decreased over time, that may indicates an increase in oxygen content. However, the sample with the highest Ni content (x=0.125) at c=0.19 suffered phase transition "rhombohedral-orthorhombic structures", which cannot be explained by the oxygen absorption. Probably, this effect was due to the rearrangement of the ions and vacancies between crystal sublattices of manganite.
19
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Structure and Magnetism of MBE-Grown Co/Cu Multilayers

80%
Baczewski L. T., Wawro A., Domagała J., Pełka J., Szewczyk A., Nabiałek A.
Acta Physica Polonica A
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1997
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vol. 91
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issue 2
315-319
EN
Structural and magnetic properties of Co/Cu multilayers deposited in the ultra-high vacuum molecular beam epitaxy system on glass substrates with different modulations periods were investigated. A structural characterization was performed by means of RHEED and Auger spectroscopy (in situ), small angle X-ray reflectivity and scanning tunneling microscopy. The samples obtained have a textured, polycrystalline layered structure for deposition at room temperature. Magnetization and in-plane magnetoresistance measurements were performed as a function of Cu and Co layer thicknesses. An influence of different buffers and of interface quality on magnetic properties was investigated.
20
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Magnetism and Specific Heat of TmRhX (X = Ga, Ge) Compounds

80%
Baran S., Przewoźnik J., Szytuła A.
Acta Physica Polonica A
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2013
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vol. 124
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issue 6
998-1001
EN
Magnetic and specific heat data of the TmRhX (X = Ga, Ge) compounds are reported. These compounds crystallize in an orthorhombic crystal structure of the TiNiSi-type (space group Pnma). Magnetic data indicate that the compounds are antiferromagnets with the Néel temperature T_{N} equal to 3.9 K for TmRhGa and 6.0 K for TmRhGe. Magnetic susceptibility of TmRhGe has an additional peak at T_{t} = 10.6 K. In TmRhGe temperature dependence of χ"(T), the positions of both the peaks at T_{N} and T_{t} change with frequency indicating a relaxation process. These data suggest that with the decreasing temperature, first a cluster glass state and next the long-range aniferromagnetic order exists.
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