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Tytuł:
Magnonic Spectra of Ferromagnetic Composites Versus Magnetization Contrast
Autorzy:
Krawczyk, M.
Puszkarski, H.
Powiązania:
https://bibliotekanauki.pl/articles/1968941.pdf
Data publikacji:
1998-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Gg
Opis:
It had been shown recently that the calculated magnonic spectra of two-dimensional periodic ferromagnetic composites can present frequency ranges forbidden for the propagation of magnon excitations throughout the composite. However, those forbidden energy gaps were found to be highly sensitive to the exchange contrast between the component ferromagnetic materials but were very weakly sensitive to the contrast in spontaneous magnetizations of the two materials. Accordingly, in this paper we introduce a new mathematical definition of the exchange field acting in inhomogeneous medium. With this new definition the present theory gives magnonic spectra reasonably sensitive to magnetization contrast, as they should be from the physical viewpoint; moreover, the magnetization contrast now becomes a gap-creating factor as well.
Źródło:
Acta Physica Polonica A; 1998, 93, 5-6; 805-810
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Conductivity and Magnetism of Magnetic Oxides
Autorzy:
Gehring, G. A.
Powiązania:
https://bibliotekanauki.pl/articles/2012877.pdf
Data publikacji:
2000-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
75.50.Gg
Opis:
In a stoichiometric oxide the energy for the magnetic ordering is due to superexchange. This depends on the virtual transfer of a d electron from the transition ion to the neighbouring oxygen. When the oxide is p-doped there are compensating holes on the oxygen or the transition ion becomes mixed valent. The oxide may then conduct. The same transfer integral enters both the expression for the antiferromagnetic superexchange and the band width of the mobile carriers. Thus materials with a large antiferromagnetic exchange energy will be expected to have a relatively wide conduction band in the doped state and hence to have a high conductivity. In this paper the difference is explored between the materials in which there is true antiferromagnetism and those which are ferrimagnetic. In the antiferromagnets the carriers must destroy the magnetic order as they move. This behaviour is well known from the cuprates. In ferrimagnets the carriers may be able to move entirely on one sublattice. This occurs in Fe$\text{}_{3}$O$\text{}_{4}$ and probably in the doped garnets. In the case where motion is on one sublattice then doping does not destroy the magnetism and there is a relatively small magnetoresistance. An interesting feature is that unlike the cuprates the ferrimagnets do not become good metals at any doping but exhibit hopping conductivity. We explain the apparent paradox that the best conductivity is actually observed in materials where the conduction is only allowed when the antiferromagnetism has been quenched and that the conductivity in ferrimagnets is low.
Źródło:
Acta Physica Polonica A; 2000, 97, 1; 175-184
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties of Zinc Doped Ferrites
Autorzy:
Abd El-Ati, M. I.
Kafafy, Aziz M.
Tawfik, A.
Powiązania:
https://bibliotekanauki.pl/articles/1887816.pdf
Data publikacji:
1991-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Gg
75.50.Dd
Opis:
A series of samples of the system Co$\text{}_{1-x}$Zn$\text{}_{x}$Fe$\text{}_{2}$O$\text{}_{4}$ (x = 0.0, 0.3, 0.4, 0.5 and 0.8) have been prepared by the usual ceramic technique. X-ray analysis shows that they are cubic spinel (single phase). The lattice parameter a and the bulk density D are measured for the samples. The substitution experiments replacing Co$\text{}^{2+}$ by Zn$\text{}^{2+}$ furnish new significant fact concerning the magnetic behaviour of ferrites. The magnetic strength of the magnetic ions on the Band A-sites can be varried relative to each other by the substitution of Zn$\text{}^{2+}$. The increase of density of the composition increases the magnetic interaction of the dipole moment at the B-sites.
Źródło:
Acta Physica Polonica A; 1991, 79, 6; 889-894
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Single-Ion Rare Earth Anisotropy in ThMn$\text{}_{12}$-Type Compounds
Autorzy:
Stefański, P.
Powiązania:
https://bibliotekanauki.pl/articles/1931244.pdf
Data publikacji:
1994-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Gw
75.50.Gg
Opis:
The single-ion rare earth anisotropy was investigated in ThMn$\text{}_{12}$-type compounds. For this purpose the crystal electric field parameter values were studied. In these compounds, described by formula RFe$\text{}_{12-x}$T$\text{}_{x}$, R = rare earth, T = Ti, V, Cr, Mo, W and Si, the T atoms have strong crystallographic site preference changing the local crystal electric field potential which "sees" the rare earth ion. The crystal electric field potentials A$\text{}_{2}^{0}$ were calculated considering this site preference. The summations were performed taking into account the nearest neighborhood of the rare earth ion according to the recent results of band structure calculations. The charges of the surrounding Fe and T atoms were established applying the chemical bond model proposed by Pauling. The absolute value of A$\text{}_{2}^{0}$ decreases when the content of vanadium increases in 8(i) position, which is in agreement with experimental data. Localization of Si atoms in 8(j) and 8(f) causes a decrease in A$\text{}_{2}^{0}$. The $\text{}^{155}$Gd Mössbauer spectroscopy data confirm this fact. Miedema's "macroscopic" atom model of cohesion in alloys was applied for interpretation of the role of T atoms in the isomer shift and volume effects.
Źródło:
Acta Physica Polonica A; 1994, 85, 3; 615-621
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Fe substitution on structural and magnetic properties of NiCr₂O₄
Autorzy:
Mohanty, P.
Prinsloo, A.
Sheppard, C.
Roos, W.
Powiązania:
https://bibliotekanauki.pl/articles/1048307.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Gg
75.60.-d
Opis:
At room temperature, the normal oxide spinel NiCr₂O₄ is tetragonally distorted and crystallizes in the I4₁/amd space group due to cooperative Jahn-Teller ordering driven by the orbital degeneracy of tetrahedral Ni²⁺. The ferrimagnetic Curie temperature (T_{C}) for NiCr₂O₄ is 74 K. The magnetic moments of NiCr₂O₄ are composed of a ferrimagnetic (longitudinal) and an antiferromagnetic (transverse) component. Exchange interaction between the magnetic cations influences the overall magnetic properties of the compound. Present work focuses on the modification of structural and magnetic properties upon substituting Fe at Cr site in NiCr₂O₄ with the motivation of changing the magnetic exchange interaction. In order to do so, single phase Ni(Cr_{0.5}Fe_{0.5})₂O₄ samples were prepared by co-precipitation techniques, while controlling the pH of precipitation. Upon Fe substitution, crystal structure was not affected much contrary to the earlier reports. In order to determine the oxidation state of each elements X-ray photoelectron spectroscopy (XPS) was performed. T_{C} was found to increase dramatically above 300 K, confirmed both from temperature and field dependent dc-magnetization studies.
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 574-577
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties of $Ni_{0.3}Zn_{0.7}Fe_2O_4$ Ferrites with Iron Ions Partly Substituted by Europium
Autorzy:
Ušák, E.
Ušáková, M.
Šoka, M.
Vašut, D.
Powiązania:
https://bibliotekanauki.pl/articles/1398263.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Gg
75.30.-m
Opis:
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.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 717-719
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetism in $RCo_{2}$ (R = Dy, Ho, Er, Tm) Under Hydrostatic Pressure
Autorzy:
Prchal, J.
Šebesta, J.
Valenta, J.
Míšek, M.
Turčinková, D.
Lapčák, L.
Prokleška, J.
Kratochvílová, M.
Sechovský, V.
Powiązania:
https://bibliotekanauki.pl/articles/1369111.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.En
75.50.Gg
Opis:
The short-range parimagnetic configurations, observed in the heavy rare-earth $RCo_{2}$ compounds in paramagnetic range far above the Curie temperature $T_{C}$, consist in formation of ferromagnetic cobalt clusters antiferromagnetically coupled to the neighboring R magnetic moments. The characteristic temperature of the onset of parimagnetism $T_{f}$ is very sensitive to changes of external conditions like pressure or composition. The pressure coefficients $∂T_{f}$/∂p and $∂T_{C}$/∂p are comparable, indicating a close connection of underlying mechanisms. Our recent measurements indicate systematic evolution of the pressure coefficients with spanning the rare-earth series from Dy through Tm in $RCo_{2}$ with a specific case $TmCo_{2}$.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 288-289
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
About the Role of Fe-Ions in the Formation of Magnetocaloric Effect in $Ho(Co_{1-x}Feₓ)₂$ Compounds
Autorzy:
Anikin, M.
Tarasov, E.
Kudrevatykh, N.
Osadchenko, V.
Zinin, A.
Powiązania:
https://bibliotekanauki.pl/articles/1387987.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.50.Gg
Opis:
A study of crystalline structure, magnetic and magnetocaloric properties of $Ho(Co_{1-x}Feₓ)₂$ (x = 0.09, 0.12) intermetallic compounds has been undertaken. Phase composition was controlled by X-ray diffraction analysis. Magnetic properties were measured within the temperature range 4.2-350 K in magnetic fields up to 7 T. Magnetic ordering temperatures corresponding to paramagnetic-ferrimagnetic phase transitions were found to be 199 K and 258 K respectively. Temperature dependences of heat capacity for these compounds have been inferred for the temperature interval 77-340 K. Comparison of magnetocaloric effect (MCE) values determined by direct measurement and by calculation was carried out as well. It was found that significant MCE peak broadening occurs for higher iron concentration in the compound.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 635-637
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Influence of Compressive Stresses on the Properties of Inductive Electronics Components
Autorzy:
Salach, J.
Nowak, P.
Powiązania:
https://bibliotekanauki.pl/articles/1031009.pdf
Data publikacji:
2018-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Gg
75.30.-m
Opis:
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.
Źródło:
Acta Physica Polonica A; 2018, 133, 4; 1053-1055
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Presence of Parimagnetism in $Ho(Co_{1-x}Si_{x})_{2}$ Under Hydrostatic Pressure
Autorzy:
Valenta, J.
Prchal, J.
Kratochvílová, M.
Míšek, M.
Sechovský, V.
Powiązania:
https://bibliotekanauki.pl/articles/1372511.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.En
75.50.Gg
Opis:
A new configuration of cobalt magnetic moments with respect to rare-earth ones on local level, named as parimagnetism, surviving above the Curie temperature was determined few years ago for $ErCo_{2}$. Occurrence of parimagnetism has recently been confirmed also for $HoCo_{2}$. In this paper we present results manifesting considerable composition and hydrostatic-pressure influence on characteristic temperatures of magnetism in $Ho(Co_{1-x}Si_{x})_{2}$ compounds and draw a preliminary scenario analyzing the exchange interactions involved.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 406-408
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Phase Transitions and Thermal Properties of $Ho(Co_{1-x}Si_x)_2$ Compounds
Autorzy:
Vasylyev, D.
Prokleška, J.
Sechovský, V.
Powiązania:
https://bibliotekanauki.pl/articles/1813682.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.50.Gg
Opis:
The specific heat of $HoCo_2$ and $Ho(Co_{0.95}Si_{0.05})_2$ was measured as a function of temperature in several constant magnetic fields up to 8 T. A data analysis allowed us to determine the isothermal entropy change and the magnetocaloric effect in a wide temperature range. The considerable values of the magnetocaloric effect in the vicinity of the magnetic ordering transition are qualifying both compounds as suitable for magnetic refrigeration purposes. The magnetic phase transition temperature $(T_C)$ increases from 77 K for $HoCo_2$ to 103 K for $Ho(Co_{0.95}Si_{0.05})_2$ while the large magnetocaloric effect in the vicinity of TC is maintained, which demonstrates possible ways of tuning the operating temperatures of the magnetic refrigerant.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 347-350
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin Reorientation and Exchange Coupling in the Dy$\text{}_{1-x}$Er$\text{}_{x}$Fe$\text{}_{10}$Si$\text{}_{2}$ Compounds
Autorzy:
Stefański, P.
Kowalczyk, A.
Skoryna, D.
Szlaferek, A.
Wrzeciono, A.
Powiązania:
https://bibliotekanauki.pl/articles/1929845.pdf
Data publikacji:
1994-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Gw
75.50.Gg
Opis:
The structural and magnetic properties of Dy$\text{}_{1-x}$Er$\text{}_{x}$Fe$\text{}_{10}$Si$\text{}_{2}$ are investigated. X-ray analysis reveals that these compounds are of the tetragonal ThMn$\text{}_{12}$ structure. In this structure the rare earth atoms occupy one crystallographic position 2(a). The unit cell contains 26 atoms. The spin reorientation temperature, T$\text{}_{SR}$, was measured from the temperature dependence of the initial susceptibility using an ac bridge of mutual inductance of the Harsthorn type. Dy$\text{}^{+3}$ and Er$\text{}^{+3}$ have opposite contributions to the entire magnetic anisotropy. The spin reorientation temperature is found to be about 271 K in DyFe$\text{}_{10}$Si$\text{}_{2}$ and 48 K in ErFe$\text{}_{10}$Si$\text{}_{2}$. The values are discussed applying the crystal field model. The value of the rare earth-transition metal exchange coupling constant J$\text{}_{RFe}$/k$\text{}_{B}$ derived from the mean-field model analysis of the Curie temperature is about -13 K. The Fe-Fe exchange integral is much higher and is equal to about 75 K.
Źródło:
Acta Physica Polonica A; 1994, 85, 2; 259-262
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ground State Properties of Tb$\text{}^{3+}$ Ion in TbNi$\text{}_{10}$Si$\text{}_{2}$
Autorzy:
Stefański, P.
Suski, W.
Wochowski, K.
Mydlarz, T.
Powiązania:
https://bibliotekanauki.pl/articles/1964565.pdf
Data publikacji:
1997-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Gw
75.50.Gg
Opis:
Ground state properties of Tb$\text{}^{3+}$ ion were investigated in the tetragonal ThΜn$\text{}_{12}$-type TbNi$\text{}_{10}$Si$\text{}_{2}$ compound on the basis of temperature dependence of the paramagnetic susceptibility and magnetization measurements. The rare earth temperature dependence of the susceptibility was calculated using the Van Vleck equation. The Γ$\text{}_{t5}^{(1)}$ doublet is suggested to be a ground state separated by 9 K from the first excited singlet Γ$\text{}_{t1}^{(2)}$. The magnetic moment associated with the ground state doublet agrees with saturation magnetization data at 4.2 K. The overall crystal field splitting is estimated to be 105 K.
Źródło:
Acta Physica Polonica A; 1997, 92, 2; 281-284
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mechanisms of the Magneto-Optical Activity of Rare-Earth Ions in Rare-Earth Iron Garnet Single Crystals
Autorzy:
Tsidaeva, N.
Abaeva, V.
Magkoev, T.
Powiązania:
https://bibliotekanauki.pl/articles/1490761.pdf
Data publikacji:
2012-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Gg
78.20.Ls
Opis:
The magnetic and magneto-optical properties of the typical representatives of three rare-earth iron garnets (RIG) groups: with heavy rare-earth elements Yb, Er, Dy, Tb; with elements from the middle of lanthanide series Gd, Sm, and with light rare-earth element Nd are presented. In contradistinction to other work on the Faraday rotation, which were done only at 1152 nm (8696 $cm^{-1}$), here we present FR spectra obtained in the energy region 5500-20000 $cm^{-1}$ with high optical resolution. The investigations have been done at temperatures of 5, 82, 130, 295 K using magnetic field up to 25 kOe applied parallel to the [111] crystallographic axis of the crystals. It has been shown that the contribution proportional to the magnetic field and independent of temperature to the mixing of the ground state multiplets exceeds the paramagnetic contribution in YbIG, ErIG, GdIG, SmIG. In Tb and Dy iron garnets contributions from the two mechanisms have opposite signs, and the paramagnetic mechanism gives the greatest contribution to the Faraday rotation. Nevertheless, the contribution of the diamagnetic mechanism, caused by the influence of the exchange field in the iron sublattices on rare-earth ions, is significant, and it is necessary to take it into account. Anomalously large magneto-optical activity is observed in NdYIG. This is the result of contributions of the same sign and approximately equal in magnitude from the paramagnetic and diamagnetic mechanisms.
Źródło:
Acta Physica Polonica A; 2012, 121, 1; 74-77
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hyperfine Field in YIG with Charged Substitution
Autorzy:
Kohout, J.
Štĕpánková, H.
Englich, J.
Novák, P.
Kučera, M.
Nitsch, K.
Powiązania:
https://bibliotekanauki.pl/articles/2013158.pdf
Data publikacji:
2000-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.60.-k
75.50.Gg
Opis:
$\text{}^{57}$Fe NMR spectra were measured on thin films of yttrium iron garnet with divalent (Ca$\text{}^{2+}$) and tetravalent (Ge$\text{}^{4+}$) cation substitutions using the spin echo technique at 4.2 K. A series of Y$\text{}_{3-x}$Ca$\text{}_{x}$Fe$\text{}_{5-x}$Ge$\text{}_{x}$O$\text{}_{12}$ samples with 0 ≤ x ≤ 0.0 5 was prepared by an epitaxial growth from BaO/B$\text{}_{2}$O$\text{}_{3}$/BaF$\text{}_{2}$ flux on gadolinium gallium garnet substrate. Satellite lines corresponding to the iron ions having the Ge$\text{}^{4+}$ and Ca$\text{}^{2+}$ in their neighbourhood were identified. The sample with the germanium content of x(Ge) = 0.004 and (110) substrate orientation was used for a detailed study: NMR spectra of this sample were measured in an external magnetic field of 0.1 T applied along several directions in the plane of the film. The modification of the isotropic part and the anisotropy tensor of the hyperfine interaction caused by the Ge$\text{}^{4+}$ substituent were obtained from the experimental data. The results were compared with those previously reported for trivalent substitution (Ga$\text{}^{3+}$).
Źródło:
Acta Physica Polonica A; 2000, 97, 3; 519-522
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
$\text{}^{57}$Fe Hyperfine Field Anisotropy in Ferrites and its Relation to the Non-Uniformity of the Ionic Surrounding
Autorzy:
Štepánková, H.
Englich, J.
Kohout, J.
Powiązania:
https://bibliotekanauki.pl/articles/2013366.pdf
Data publikacji:
2000-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.60.-k
75.50.Gg
Opis:
The hyperfine field anisotropy tensors, obtained from analysis of $\text{}^{57}$Fe NMR spectra for iron sites in various magnetic oxides (barium hexaferrite, lithium spinel, magnetite and yttrium-iron garnet) were used to investigate the relation between the hf anisotropy and surrounding ionic arrangement. While a reasonable correlation has been found when the distribution of the nearest cations was considered, no correlation was obtained between the hyperfine field anisotropy and the positions of the nearest oxygen anions.z
Źródło:
Acta Physica Polonica A; 2000, 97, 5; 757-760
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Field-Induced Slow Magnetic Relaxation in Mn₉W₆ Cluster-Based Compound
Autorzy:
Konieczny, P.
Pełka, R.
Chorazy, S.
Podgajny, R.
Sieklucka, B.
Wasiutyński, T.
Powiązania:
https://bibliotekanauki.pl/articles/1032251.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Xx
75.40.Cx
75.50.Gg
Opis:
Magnetic measurements of a three-dimensional (3D) molecular magnet built of Mn₉[W(CN)₈]₆ clusters have been carried out to study its static and dynamic properties. Measurements of ac susceptibility in the presence of static magnetic field revealed slow magnetic relaxations. It was found that for the 120 Hz wave frequency the optimal static field which maximizes the imaginary component of the ac susceptibility is about 500 Oe.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 884-886
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Open Source Implementation of Different Variants of Jiles-Atherton Model of Magnetic Hysteresis Loops
Autorzy:
Szewczyk, R.
Cheng, P.
Powiązania:
https://bibliotekanauki.pl/articles/1030747.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Bb
75.50.Gg
75.60.Ej
Opis:
Jiles-Atherton model is one of the most advanced and most popular models of magnetic hysteresis loop. However, this model is considering different physical phenomena and computational issues. As a result, cross-validation of the results of modelling performed by different authors became difficult. For this reason, the open-source MATLAB/OCTAVE based implementation of Jiles-Atherton model was developed. Proposed implementation covers isotropic model of magnetic hysteresis loops as well as uniaxial and grain oriented electrical steel anisotropy. Moreover, the corrections proposed by Venkataraman together with different approaches to derivative of the anhysteretic magnetization are considered. Developed library is freely available together with the examples of magnetic hysteresis loops. As a result, it can be the base for further development of Jiles-Atherton model for better understanding of magnetization process as well as modelling the inductive components.
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 654-656
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelling of the Magnetic Characteristics of Isotropic and Anisotropic Materials for Sensor Applications
Autorzy:
Szewczyk, R.
Powiązania:
https://bibliotekanauki.pl/articles/1813527.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.60.Ej
75.50.Gg
75.50.Kj
Opis:
The following paper presents the results of modelling of the magnetic characteristics of isotropic (Ni-Zn ferrite) and anisotropic material ($Fe_{40}Ni_{38}Mo_4B_{18}$ amorphous alloy in as quenched state), both useful for sensor applications. For the modelling an extended Jiles-Atherton model was used. Extension of the model connects model's parameter k, describing average energy required to break pinning site, with magnetic state of the material. Such extension of the model is reasonable from the physical point of view. Good agreement between experimental data and modelling confirms that the extended Jiles-Atherton model creates the possibility of modelling of magnetic characteristics of both isotropic and anisotropic magnetic cores.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 67-70
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Biogenic Magnetite Nanoparticle Ensemble Use in MRI Diagnostics
Autorzy:
Strbak, O.
Krafcik, A.
Teplan, M.
Gogola, D.
Kopcansky, P.
Frollo, I.
Powiązania:
https://bibliotekanauki.pl/articles/1202318.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Gg
75.50.Tt
87.61.-c
Opis:
We present a simple analytical tool, which allows the calculation of the MRI diagnostics feasibility of the biogenic magnetite nanoparticles. Elevated levels of these particles are usually linked to the pathological processes, especially to neurodegenerative disorders. We showed theoretically that the biogenic magnetite itself is not sufficient for the non-invasive diagnostics and must be extended with the total iron incorporated in other biological structures.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 388-389
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Effect of a Random Crystal-Field on the Mixed Ising Spins (1/2, 3/2)
Autorzy:
Bahmad, L.
Benayad, M.
Benyoussef, A.
El Kenz, A.
Powiązania:
https://bibliotekanauki.pl/articles/1504480.pdf
Data publikacji:
2011-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.50.+q
75.10.Hk
75.50.Gg
Opis:
We study the magnetic properties of a mixed Ising ferrimagnetic system, in which the two interacting sublattices have spins σ,(±1/2) and spins S,(±3/2,±1/2) in the presence of a random crystal field, with the mean field approach. The results obtained, using mean field approach and Monte Carlo simulation, show the appearance of a new ferrimagnetic phase, namely the partly ferrimagnetic phase ($m_{σ}$ = -1/2 , $m_{S}$ = +1). Consequently, three topologically different types of phase diagrams have been given by mean field approach. The effect of increasing the exchange interaction parameter J, at very low temperature is also investigated.
Źródło:
Acta Physica Polonica A; 2011, 119, 6; 740-746
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Semiconducting Properties of $Cu_5SbO_6$
Autorzy:
Groń, T.
Filipek, E.
Dąbrowska, G.
Duda, H.
Mazur, S.
Kukuła, Z.
Pawlus, S.
Powiązania:
https://bibliotekanauki.pl/articles/1409627.pdf
Data publikacji:
2012-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
72.20.Pa
75.50.Gg
Opis:
Thermoelectric power, electrical resistivity, I-V characteristics, relative electrical permittivity, dc magnetization and ac magnetic susceptibility measurements carried out on $Cu_5SbO_6$ showed p-type semiconducting behaviour with the activation energy of 0.24 eV as well as ferrimagnetic order with the Néel temperature of 5.2 K. The effective magnetic moment of 5.857 $μ_{B}$/f.u. revealed the orbital contribution to the magnetic moment. Large value of the relative electrical permittivity indicated that the $Cu^{2+}$ ions with the unscreened and unfilled electron shells are responsible for the polarizability and forming of electric dipoles.
Źródło:
Acta Physica Polonica A; 2012, 122, 6; 1105-1107
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structure of Iron Oxide Nanoparticles Studied by $\text{}^{57}Fe$ NMR
Autorzy:
Křišťan, P.
Chlan, V.
Štěpánková, H.
Řezníček, R.
Görnert, P.
Payer, P.
Powiązania:
https://bibliotekanauki.pl/articles/1378149.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.60.-k
75.50.Gg
75.50.Tt
Opis:
In this work we apply nuclear magnetic resonance (NMR) spectroscopy of $\text{}^{57}Fe$ nuclei for investigation of submicron and nanocrystalline iron oxide systems. The studied iron oxide particles are obtained from ferrous hydroxide gels (prepared from $FeCl_{2}$ and KOH) by aging at elevated temperatures (90 °C) with $KNO_{3}$ as oxidant. The $\text{}^{57}Fe$ NMR spectra of the samples are measured in temperature range 4.2-370 K in a zero external magnetic field. Signals of $\text{}^{57}Fe$ nuclei assigned to tetrahedral and octahedral iron sites are well resolved. The NMR spectra and their temperature dependences are compared with those of stoichiometric and nonstoichiometric magnetite single crystals, as well as with samples of maghemite.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 138-139
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties of Divalent (Ni,Sn,Zn)- Tetravalent (Ru,Sn) Ionic Mixtures of Substituted Ba Ferrite
Autorzy:
Sláma, J.
Grusková, A.
González Angeles, A.
Šoka, M.
Dosoudil, R.
Powiązania:
https://bibliotekanauki.pl/articles/1367766.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Gg
75.50.Vv
77.22.Ej
Opis:
The drop of coercivity, while preserving the saturation magnetic polarisation $J_{S}$ of substituted M-type Ba hexaferrites with composition $BaFe_{12-2x}(Me_{1}Me_{2})_{x}O_{19}$, was studied. Divalent $Me_{1}$=Ni, Zn, Sn and tetravalent $Me_{2}$=Ru, Sn ionic combinations were used in various compounds. Mössbauer spectroscopy was used to reveal sites of replacement of the $Fe^{3+}$ ions by $Ru^{4+}$ and $Sn^{4+}$. The $Ni^{2+}$, $Zn^{2+}$ and $Sn^{2+}$ occupation sites were identified as well. Strong drop of coercivity difference Δ $H_{c}(x)$ near x=0.1 and slight decrease of Δ $H_{c}(x)$ close to x=0.3 was obtained for suitable coupling of $Me_{1}^{2+}$ and $Me_{2}^{4+}$ ions.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 172-173
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Elimination of Magnetic Nanoparticles with Various Surface Modifications from the Bloodstream in vivo
Autorzy:
Tomasovicova, N.
Khmara, I.
Koneracka, M.
Zavisova, V.
Kubovcikova, M.
Antal, I.
Kovac, J.
Muckova, M.
Kopcansky, P.
Powiązania:
https://bibliotekanauki.pl/articles/1032816.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Gg
75.50.Tt
87.85.jj
Opis:
The magnetic nanoparticles with the core diameter 10 nm stabilized by sodium oleate and bovine serum albumin in phosphate buffer have been modified by different biocompatible substances such as poly(ethylene glycol) (PEG), dextran (DEX), and polyvinylpyrrolidone (PVP). Prepared biocompatible magnetic fluids were characterized to obtain the particle size distribution using scanning electron microscopy and the dynamic light scattering method. To study the elimination of different modified magnetic nanoparticles from bloodstream, the biocompatible samples were applied intravenously to the mice bloodstream with further blood specimens collecting in given time intervals. Magnetic moment of the lyophilized blood samples was measured by SQUID magnetometer. Time dependence of magnetic moment of magnetic nanoparticles and magnetic nanoparticles modified by DEX, PEG and PVP normalized to the Fe₃O₄ showed that the circulation time of magnetic nanoparticles in the bloodstream depends on the substance used for modification. The unmodified magnetic nanoparticles were trapped by reticuloendothelial system within 1 h while magnetic nanoparticles modified by DEX, PEG and PVP circulated in blood up to 3 h.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 1159-1161
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structural characterization and magnetic properties of CuCr₂Te₄ spinel obtained by mechanical alloying and heat treatment
Autorzy:
Karolus, M.
Maciążek, E.
Panek, J.
Kubisztal, M.
Groń, T.
Powiązania:
https://bibliotekanauki.pl/articles/1154138.pdf
Data publikacji:
2016-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Gg
75.50.Tt
81.10.Jt
Opis:
CuCr₂Te₄ can be obtain by mechanical alloying followed by heat treatment. The obtained phase crystallizes in the spinel-type structure of the space group Fd3m. The calculated crystallite size equals to 100 nm. Magnetic susceptibility measurements showed ferrimagnetic order below 21 K.
Źródło:
Acta Physica Polonica A; 2016, 130, 4; 859-861
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reappearance of Antiferromagnetic Order in $Nd_{0.9}Ca_{0.1}BaCo_{2}O_{5+δ}$ for δ > 0.51
Autorzy:
Piętosa, J.
Kolesnik, S.
Puźniak, R.
Dabrowski, B.
Powiązania:
https://bibliotekanauki.pl/articles/1374353.pdf
Data publikacji:
2014-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Kz
75.50.Gg
62.50.-p
Opis:
The absence of the antiferromagnetic order in $Nd_{0.9}Ca_{0.1}BaCo_2O_{5.5}$ has been found to remain unchanged by applying a hydrostatic pressure of 10 kbar. In magnetic studies of polycrystalline $Nd_{0.9}Ca_{0.1}BaCo_2O_{5+δ}$ (δ=0.07-0.69), we have found a reappearance of the antiferromagnetic phase, caused by an increase in oxygen index δ above 0.51 related to extra oxygen ions addition into the $NdO_{δ}$ plane. For the samples with δ=0.555 and 0.59, a coexistence of well developed antiferromagnetic phase with ferrimagnetic one is evidenced.
Źródło:
Acta Physica Polonica A; 2014, 126, 4a; A-50-A-52
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis and Magnetic Properties of $CuCr_{1.65}Se_4$ Nanoparticles
Autorzy:
Maciążek, E.
Panek, J.
Kubisztal, M.
Karolus, M.
Groń, T.
Duda, H.
Powiązania:
https://bibliotekanauki.pl/articles/1376067.pdf
Data publikacji:
2014-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Gg
75.50.Tt
81.10.Jt
Opis:
$CuCr_{1.65}Se_{4}$ nanoparticles crystallize in the monoclinic $Cr_{2}Se_{3}$-type structure of the space group I2/m. The average crystallite size basing on the line broadening is less than 10 nm. With decrease of the size of grains a change from ferromagnetic to ferrimagnetic order, a lack of the magnetization saturation and a strong spin-orbit coupling visible in the large value of the Landé factor $g_{χ}$ = 2.72 are observed. The change in magnetic order is caused by the change of the crystalline symmetry from the cubic phase to monoclinic one.
Źródło:
Acta Physica Polonica A; 2014, 126, 5; 1137-1139
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hopkinson effect in soft and hard magnetic ferrites
Autorzy:
Sláma, J.
Ušáková, M.
Šoka, M.
Dosoudil, R.
Jančárik, V.
Powiązania:
https://bibliotekanauki.pl/articles/1053131.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Gg
75.30.Kz
75.30.Cr
Opis:
The dependences of the susceptibility of selected spinel and hexagonal ferrites on temperature are analyzed. The susceptibility shows a peak just below the Curie temperature T_{C} due to the Hopkinson effect during the heating. The appearance of this effect is associated with a transition from the region of stable magnetization state to superparamagnetic relaxations of the magnetic particles. It is in contrast to other explanations of the Hopkinson effect. These results are compared with measured particles size and with scanning electron microscope micrographs of both types of ferrites.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 762-764
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetism in $NdMnO_{3+δ}$ Studied by the Single Crystal Neutron Diffraction
Autorzy:
Mihalik, M.
Maťaš, S.
Vavra, M.
Powiązania:
https://bibliotekanauki.pl/articles/1368766.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.-g
75.30.-m
75.50.Gg
Opis:
We present the single crystal neutron diffraction experiment performed on the $NdMnO_{3+δ}$ compound. The aim of the experiment was to study/revisit the magnetic structure of the compound. We have confirmed the ordering of Mn sublattice below $T_{N}$=85.5 K and confirmed that the Nd sublattice orders below $T_{1}$ ≈ 20 K with Nd moments aligned parallel to the b-axis.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 284-285
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Effects of the Random Transverse Crystal Field on the Spin-1 Model
Autorzy:
Albayrak, E.
Powiązania:
https://bibliotekanauki.pl/articles/1399269.pdf
Data publikacji:
2015-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Hk
75.30.Kz
75.50.Gg
Opis:
The effects of random transverse crystal field are investigated in the mean-field approximation on the spin-1 model. The transverse crystal field is applied on a lattice in a bimodal random distribution with a tunable parameter adjusting the strength of one mode with respect to the other one. Then, the phase diagrams are calculated on the reduced temperature-transverse crystal field planes for given values of probability p and coordination number q at zero external magnetic field h. It was found that the model gives both second- and first-order phase transitions and tricritical points which is a well-known behavior of the spin-1 model. In addition, the model also yields critical end points and end points for the first-order phase transition lines for appropriate p values.
Źródło:
Acta Physica Polonica A; 2015, 127, 3; 818-822
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Giant Magnetoelectricity in Aluminium Substituted Y-Hexaferrites
Autorzy:
Novák, P.
Chlan, V.
Knížek, K.
Powiązania:
https://bibliotekanauki.pl/articles/1506886.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.85.+t
71.20.Ps
75.50.Gg
Opis:
The electron structure of Al containing Y-hexaferrite that exhibits the giant magnetoelectricity is calculated. Results show strong preference of Al for octahedral sites. Orbital moment of some of the iron ions is found to be unusually large.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 723-724
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Cation Distribution in Fe$\text{}_{3(1-\delta)}$O$\text{}_{4}$ and Low Level Doped Fe$\text{}_{3-x}$M$\text{}_{x}$O$\text{}_{4}$, M=Ti, Zn, Al
Autorzy:
Kąkol, Z.
Kozłowski, A.
Sabol, J.
Metcalf, P.
Honig, J. M.
Powiązania:
https://bibliotekanauki.pl/articles/1861287.pdf
Data publikacji:
1994-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.80.Ga
75.30.Cr
75.50.Gg
Opis:
Systematic magnetic saturation moment and electrical resistivity measurements of the Fe$\text{}_{3(1-\delta)}$O$\text{}_{4}$ and Fe$\text{}_{3-x}$M$\text{}_{x}$O$\text{}_{4}$ (M = Ti, Zn, Al) are presented. Cation distributions for low level doping are proposed and compositional dependencies of the Verwey transition temperature are determined. The latter show striking similarities in their dependence on cation vacancies and dopant concentration for any extraneous cations. These data are the basis for the analysis of the correlation between the presented cations distributions and the Verwey transition.
Źródło:
Acta Physica Polonica A; 1994, 85, 1; 223-227
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Complex Permeability of LiZn/MnZn/PVC Composite Materials
Autorzy:
Dosoudil, R.
Ušáková, M.
Grusková, A.
Sláma, J.
Powiązania:
https://bibliotekanauki.pl/articles/1535468.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.80.Tm
75.50.Gg
76.50.+g
Opis:
The effect of particle content, size, and the fraction ratio of the double LiZn/MnZn ferrite filler in hybrid LiZn/MnZn/PVC composites on the frequency dispersion of complex permeability has been studied in the 1 MHz-3 GHz frequency range. The obtained relaxation type of permeability dispersion is due to the domain wall resonance, the natural ferromagnetic resonance, and the relaxation of magnetization rotation. The permeability and resonance/relaxation frequency of composites seem to be strongly affected by the change of particle content and fraction ratio of the double ferrite filler rather than by particle size.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 1049-1050
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Frequency Variation of Complex Permeability in Dual Ferrite Filler - Single Polymeric Matrix Composites
Autorzy:
Dosoudil, R.
Ušáková, M.
Sláma, J.
Grusková, A.
Powiązania:
https://bibliotekanauki.pl/articles/1813959.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.80.Tm
75.50.Gg
76.50.+g
Opis:
The frequency dependences of complex initial permeability for triple-component composite materials based on two different types of ferrite filler (MnZn and NiZn ferrite) and a nonmagnetic polymeric matrix (PVC) were studied in the frequency range of 10 kHz-1 GHz. The frequency dispersion of permeability is discussed by means of a dynamic model based on the superposition of the two types of magnetic resonance, the resonance of vibrating domain walls and the resonance of precessing magnetic moments in domains.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 621-624
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Pressure on Magnetic Properties of Hexacyanochromates
Autorzy:
Mitróvá, Z.
Maťaš, S.
Mihalik, M.
Zentková, M.
Arnold, Z.
Kamarád, J.
Powiązania:
https://bibliotekanauki.pl/articles/1813813.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Cr
75.50.Ee
75.50.Gg
75.50.Xx
Opis:
We present the study of pressure effect on magnetic properties of $TM^{2+}_3[Cr^{III}(CN)_6]_2 \cdot nH_2O$ ferrimagnets and ferromagnets (TM = Cr and Co) under pressures up to 0.9 GPa. Applied pressure strengthens super-exchange interaction in $Cr^{2+}$-prussian blue analogues with dominant antiferromagnetic interaction $J_{AF}$ leading to increase in the Curie temperature $T_C$ (ΔT_c/Δp = 29.0 K/GPa) and reduces $T_C$ of $Co^{2+}$-prussian blue analogues with dominant ferromagnetic interaction $J_F$ (Δ$T_c$/Δp = -1.8 K/GPa). The rise of $J_{AF}$ interaction is attributed to the enhanced value of the single electron overlapping integral S. On the other hand, the applied pressure slightly affects bonding angles between magnetic ions mediated by the cyano-bridge and reduces the strength of magnetic coupling. Changes of the magnetization curve with pressure can be attributed to changes of magnetic anisotropy. The reduction of magnetization with pressure observed on $Cr^{2+}$-prussian blue analogues can be explained by pressure induced transition from $Cr^{2+}$ high spin state to $Cr^{2+}$ low spin state. All pressure induced changes are reversible.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 469-472
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Pressure on Magnetic Properties of $TM_3[Cr(CN)_6]_2 \cdot nH_2O$ Nanoparticles
Autorzy:
Zentko, A.
Zentková, M.
Kavečanský, V.
Mihalik, M.
Mitróová, Z.
Arnold, Z.
Kamarád, J.
Cieslar, M.
Zeleňák, V.
Powiązania:
https://bibliotekanauki.pl/articles/1813843.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Cr
75.50.Ee
75.50.Gg
75.50.Xx
Opis:
Effect of pressure on magnetic properties of magnetic nanoparticles, based on Prussian blue analogues, were studied in pressures up to 1.2 GPa. The $Mn_3[Cr(CN)_6]_2 \cdot nH_2O$ and $Ni_3[Cr(CN)_6]_2 \cdot nH_2O$ nanoparticles were prepared by reverse micelle technique. Transmission electron microscopy images show nanoparticles with average diameter of about 3.5 nm embedded in an organic matrix. The characteristic X-ray peaks of nanoparticles are more diffused and broader. Systems of nanoparticles behave as systems of interacting magnetic particles. The Curie temperature $T_C$ is reduced from $T_C$ = 56 K for Ni-Prussian blue analogues to $T_C$ = 21 K for Ni-nanoparticles system and from $T_C$ = 65 K for Mn-Prussian blue analogues to $T_C$ = 38 K for Mn-nanoparticles system. One can explain this reduction of the Curie temperature and of the saturated magnetization $μ_s$ by dispersion of nanoparticles in an organic matrix i.e. by a dilution effect. Applied pressure leads to a remarkable increase in $T_C$ for system of Mn-nanoparticles (Δ$T_C$/Δp = +13 K/GPa) and to only slight decrease in $T_C$ for system of Ni-nanoparticles (Δ$T_C$/Δp = -3 K/GPa). The pressure effect follows behavior of the mother Prussian blue analogues under pressure. The increase in saturated magnetization, attributed to compression of the organic matrix, is very small.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 489-493
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Temperature Influence on the Functional Properties of Inductive Components with Mn-Zn Ferrite Cores
Autorzy:
Jackiewicz, D.
Kachniarz, M.
Bieńkowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/1030884.pdf
Data publikacji:
2018-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
84.30.Jc
75.47.Lx
75.50.Gg
Opis:
The paper presents the results of investigation of the temperature influence on the inductance and power losses in ferrite cores. Such effect can significantly influence the utility parameters of electronic devices, particularly in precision equipment. For example slight parameter change in this type of components in measuring devices can cause significant changes in output parameters. It is also equally important for mobile devices where increase of losses can limit the duration of service. Special measurement system composed of hysteresis graph, cryostat and PC was utilized to perform the experiment. The cores used during the investigation had closed magnetic circuit. In order to perform measurements of magnetic properties of the material, two sets of windings (magnetizing and sensing) were made on each core. The cores were placed in a cryostat, which was used to set the temperature value within the range from -20 to +50°C. The magnetic properties were measured by the hysteresis graph, to assess the influence of the temperature on the functional parameters.
Źródło:
Acta Physica Polonica A; 2018, 133, 4; 1038-1040
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nickel/Zinc ratio and lanthanum substitution effect on structural and magnetic properties of nickel zinc ferrites
Autorzy:
Jančárik, V.
Šoka, M.
Ušáková, M.
Harťanský, R.
Powiązania:
https://bibliotekanauki.pl/articles/1053078.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Gg
75.30.Cr
61.05.C-
Opis:
Improvement of NiZn ferrites properties by means on Ni/Zn content ratio modification and by partial substitution of Fe³⁺ ions by La³⁺ ions is presented. Ni_{x}Zn_{1-x}Fe₂O₄ and Ni_{x}Zn_{1-x}La_{0.02}Fe_{1.98}O₄ samples of small particles were prepared by self-propagated combustion method. X-ray spectroscopy was used for structural analysis, temperature dependence of magnetic susceptibility was used for evaluation of chemical and phase composition. Analysis showed that pure spinel structure without secondary phase caused by La ions for all values of Ni/Zn content was present. Noticeable growth of the magnetic susceptibility at room temperature was observed with rising of Zn²⁺ ions content.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 693-695
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Crystal Structure and Magnetic Properties of Pyrrhotite-Type Compounds $Fe_{7-y}V_{y}S₈$
Autorzy:
Selezneva, N.
Ibrahim, P.
Toporova, N.
Sherokalova, E.
Baranov, N.
Powiązania:
https://bibliotekanauki.pl/articles/1397027.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.66.Fn
75.30.Kz
75.50.Gg
Opis:
The pyrrhotite-type compounds $Fe_{7-y}V_{y}S₈$ have been synthesized and studied by means of the X-ray diffraction and magnetization measurements in order to reveal how the substitution of V for Fe affects the crystal structure, phase transition and magnetic properties. The growth of the V content in $Fe_{7-y}V_{y}S₈$ results in changes of the crystal structure and leads to a sharp decrease in the resultant magnetization, non-monotonous change of the coercive field and reduction of the magnetic ordering temperature. Unlike ferrimagnetic ordering in pyrrhotite Fe₇S₈ the compound V₇S₈ is observed to exhibit a Pauli-paramagnetic behaviour.
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 450-452
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Tb/Gd Substitution on Crystal Structure and Exchange Interactions of $Gd_{1 - x}Tb_{x}Ni_3$ Intermetallic Compounds
Autorzy:
Chrobak, A.
Bajorek, A.
Chełkowska, G.
Powiązania:
https://bibliotekanauki.pl/articles/1427373.pdf
Data publikacji:
2012-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Gg
75.30.Et
71.20.Lp
Opis:
In the paper an influence of Tb/Gd substitution on crystal structure and exchange interactions of $Gd_{1 - x}Tb_{x}Ni_3$ (x = 0.0, 0.5, 0.8, 1.0) polycrystalline compounds have been studied. The crystal structure of all samples was checked at the room temperature by means of X-ray diffraction. Exchange integrals of $R-R (J_{RR}),$ $T-T (J_{TT})$ and $R-T (J_{RT})$ atoms were evaluated from M(T) magnetization curves (2-300 K, 2 T) based on the mean field theory calculation. As it was shown the samples examined are single phase and crystallize in the PuNi_3 (space group R-3m) type of crystal structure. The Tb/Gd substitution causes the decrease of lattice parameters as well as the volume of the unit cell. With increase of the x parameter the magnetic moment of Tb atoms increases from 6.94 $μ_{B}$ (x = 0.5) to 8.12 $μ_{B}$ (x = 1). The M(T) dependence of the examined compounds depends almost 8 times stronger on exchange interactions within the R-R site than the interactions between the two antiferromagnetically coupled magnetic sublattices R-T.
Źródło:
Acta Physica Polonica A; 2012, 121, 5-6; 1132-1135
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetism in TmCo₂
Autorzy:
Šebesta, J.
Prchal, J.
Valenta, J.
Kratochvílová, M.
Sechovský, V.
Powiązania:
https://bibliotekanauki.pl/articles/1385702.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.En
75.50.Gg
71.70.Gm
Opis:
Recently a new wave of interest in physics of RCo₂ compounds has been boosted by reports on unusual magnetic short range order configurations in the heavy rare-earth RCo₂ ferrimagnets in paramagnetic state. The newly observed phenomenon called parimagnetism consists in a short-range antiferromagnetic coupling between small ferromagnetic Co clusters and the nearest rare-earth moments. This paper is devoted to results of our experimental investigation of carefully prepared and characterized samples of TmCo₂, a compound on which controversial results can be found in literature. Detailed magnetization, AC susceptibility, specific heat and electrical resistivity measurements revealed two magnetic phase transitions at 4.6 and 3.6 K, respectively. The anomalies connected with the transitions are strongly dependent on magnetic field and hydrostatic pressure. The AC susceptibility anomaly connected with the onset of parimagnetism has been found at $T_{f}$=35 K. Contrary to other heavy rare-earth RCo₂ counterparts $T_{f}$ of TmCo₂ is entirely pressure independent.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 379-381
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mean-Field and Monte Carlo Study of a Mixed Ferro-Ferrimagnetic Ternary Alloy
Autorzy:
Dely, J.
Bobák, A.
Horváth, D.
Powiązania:
https://bibliotekanauki.pl/articles/1813809.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.10.Ln
75.10.Hk
75.50.Gg
Opis:
We present a study of the magnetic properties of a mixed ferro-ferrimag-netic ternary alloy of the type $AB_p C_{1-p}$ on a cubic lattice consisting of three different Ising spins $S_A$ =3/2, $S_B$ = 2, and $S_C$ = 5/2. We employ the mean-field approximation and Monte Carlo simulation to find the compensation temperatures of the system for selected values of the parameters in the model Hamiltonian. In particular, the relation between considered mixed ferro-ferrimagnetic model and magnetic properties of the ternary metal Prussian blue analog such as $(Fe_p^{II}Mn_{1-p}^{II})_1.5$ $[Cr^{III}(CN)_6] \cdot nH_2O$ is discussed.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 461-464
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties of Nano-Crystalline Barium Ferrite Synthesized by Different Synthesis Route
Autorzy:
Ovalioglu, H.
Sozeri, H.
Kabaer, M.
Kucuk, I.
Powiązania:
https://bibliotekanauki.pl/articles/1535266.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Gg
75.50.Ss
75.50.Ww
61.72.U-
Opis:
We have synthesized $Ba_{1-x}La_{x}Fe_{12}O_{19}$ (0 ≤ x ≤ 0.4) and $BaFe_{12-y}Nd_{y}O_{19}$ (0 ≤ y ≤ 4) samples in ammonium nitrate melt and nitric acid. The effects of La and Nd doping on the microstructure and magnetic properties of $BaFe_{12}O_{19}$ were investigated. The highest coercive field was obtained for the sample having La content, x = 0.3.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 1020-1021
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Substitution and Milling on Structural and Magnetic Properties of Selected $Sm(Ni_{1-x}Co_{x})₃$ Compounds
Autorzy:
Sikora, M.
Blachliński, D.
Ociepka, K.
Prusik, K.
Bajorek, A.
Chełkowska, G.
Powiązania:
https://bibliotekanauki.pl/articles/1397029.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Cr
75.30.Sg
75.50.Gg
75.50.Vv
Opis:
The influence of substitution of Co for Ni in $Sm(Ni_{1-x}Co_{x})₃$, where x=0.0, 0,1, 0.2, on the structural and magnetic properties has been investigated. Samples with x= 0.0 and 0.2 were subjected to grinding in a high energy ball mill. The presence of a PuNi₃ type of crystal phase was evidenced for bulk crystalline and powders specimens. With an increase in the cobalt content, an increase at T_{c} was observed. From the magnetic isotherms, the magnetic entropy changes were determined both for solid and powdered samples. It has been shown that the value of the magnetic entropy change at T_c is doubled for the bulk sample with x= 0.2 but it has decreased significantly for all powdered samples.
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 486-488
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Manganese on Magnetic and Electrical Properties of the RMn$\text{}_{x}$T$\text{}_{12-x}$ Alloys
Autorzy:
Suski, W.
Wochowski, K.
Mydlarz, T.
Belan, B.
Powiązania:
https://bibliotekanauki.pl/articles/2014385.pdf
Data publikacji:
2000-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Gg
75.20.-g
75.20.En
75.50.Ee
Opis:
The magnetic and electrical properties of the tetragonal, ThMn$\text{}_{12}$-type RMn$\text{}_{x}$T$\text{}_{12-x}$ alloys (R = Y, Ce, Pr, Nd, Sm and T = Fe, Co, Ni) were studied in broad temperature and magnetic field ranges to elucidate an influence of manganese on the magnetic ordering in these materials. Magnetic properties were examined at T=1.7-300K in magnetic field up to 14T, whereas the electrical properties were examined at T=4.2-300K, on the polycrystalline samples. Majority of the samples exhibit ferro- or ferrimagnetic properties. Some samples containing larger concentration of Mn are paramagnetic in the whole temperature range. The electrical resistivity of these alloys shows metallic character.
Źródło:
Acta Physica Polonica A; 2000, 98, 5; 505-511
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Microstructure Evolution on the Coercive Forces in Low Silicon Non-Oriented Steels
Autorzy:
Petryshynets, I.
Kovac, F.
Stoyka, V.
Boruta, J.
Powiązania:
https://bibliotekanauki.pl/articles/1535233.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.En
74.25.Ha
75.50.Bb
75.50.Gg
Opis:
The magnetic properties and their dependence on the peculiarity of microstructure in low silicon non-oriented electrotechnical steels were studied in the present work. The estimation of dc magnetic properties of electrical steels was carried out by measurements of coercive forces. It was shown that the coercive force change in silicon steels is dependent on change of average grain size, crystallographic texture and homogeneity of microstructure of the materials. It was revealed that the steels possessing columnar or huge grained microstructure had the lowest measured values of coercive forces. The materials with such microstructure are characterized by a domination of (100) 〈0vw〉 crystallographic orientation.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 1013-1014
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Tracking the Evolution of Abnormal Grain Growth in Grain-Oriented Electrical Steels by Coercivity Measurements
Autorzy:
Stoyka, V.
Kovac, F.
Petryshynets, I.
Schindler, I.
Powiązania:
https://bibliotekanauki.pl/articles/1535242.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Ha
75.20.En
75.50.Bb
75.50.Gg
Opis:
The measurements of coercivity were utilised to investigate the main evolution stages of abnormal grain growth in grain-oriented electrical steels. The investigated grain-oriented steels were taken from industrial line after final cold rolling. The steels were subjected to short time annealing at elevated temperatures with high heating rates. The coercivity measurements carried out within the present work were confronted with microstructure and texture analysis in order to show the direct dependence of the measured coercivities on metallurgical characteristics of the investigated steel. It is shown that the coercivity measurements technique could capture main microstructural changes taking place in recrystallization.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 1015-1017
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Rhombohedral Distortion in Fe$\text{}_{3-y}$Zn$\text{}_{y}$O$\text{}_{4}$ at Verwey Transition
Autorzy:
Kozłowski, A.
Kąkol, Z.
Zalecki, R.
Knight, K.
Honig, J. M.
Powiązania:
https://bibliotekanauki.pl/articles/1955841.pdf
Data publikacji:
1997-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Gg
64.70.Kb
61.12.-q
Opis:
The time-of-flight neutron diffraction data were collected for two Fe$\text{}_{3-y}$Zn$\text{}_{y}$O$\text{}_{4}$ powder samples showing different order of the Verwey transition: y=0.0072 - first order, y=0.0249 - second order. Measurements were performed on spallation neutron source in ISIS Rutherford Appleton Laboratory. At low temperatures (below Verwey transition temperature T$\text{}_{V}$) clear splitting of certain reflections characteristic of rhombohedral distortion was observed for both samples. We found that this distortion is much bigger for the sample exhibiting first-order than for the sample showing second-order transition.
Źródło:
Acta Physica Polonica A; 1997, 91, 2; 443-446
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The influence of NiZnFe₂O₄ content on magnetic properties of supermalloy type material
Autorzy:
Ďáková, L'.
Füzer, J.
Dobák, S.
Kollár, P.
Fáberová, M.
Strečková, M.
Bureš, R.
Hadraba, H.
Powiązania:
https://bibliotekanauki.pl/articles/1053020.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
07.55.-w
75.60.-d
75.50.Bb
75.50.Gg
Opis:
Soft magnetic composites represent a remarkable kind of materials with wide variety of use. Magnetic properties are dependent on the materials composition and also on the method of preparation. Ni-Fe-Mo alloys (supermalloy) have high complex permeability and low eddy current losses. Soft magnetic NiZnFe₂O₄ ferrites have low coercivity and intermediate saturation magnetization. The Ni_{80}Fe_{14.7}Mo_{4.5}Mn_{0.5}Si_{0.3} (wt%) powder sample was prepared by mechanical alloying of the chemical elements for 24 h. Ni_{0.3}Zn_{0.7}Fe₂O₄ ferrite is commercially available by Sigma Aldrich. Both powders were mixed at selected ratio and uniaxially compacted at 800 MPa. In this paper, we report the experimental observations of the effects of Ni_{0.3}Zn_{0.7}Fe₂O₄ content on the electromagnetic properties of NiFeMoMnSi/Ni_{0.3}Zn_{0.7}Fe₂O₄. The samples contained 5, 10, and 15% of Ni_{0.3}Zn_{0.7}Fe₂O₄ ferrite and were sintered for 30 min at 800°C. An addition of Ni_{0.3}Zn_{0.7}Fe₂O₄ ferrite caused decrease of complex permeability and increase coercivity of the samples. The 5% of Ni_{0.3}Zn_{0.7}Fe₂O₄ sample exhibits the highest value of the real part of complex permeability (48 at 1 kHz). The 10% of Ni_{0.3}Zn_{0.7}Fe₂O₄ sample showed the lowest total magnetic losses.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 813-815
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-50 z 85

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