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Wyszukujesz frazę "75.50.-" wg kryterium: Temat


Tytuł:
Magnetoresistance and Magnetic Properties of the Double Perovskites
Autorzy:
Philipp, J. B.
Majewski, P.
Reisinger, D.
Geprägs, S.
Opel, M.
Erb, A.
Alff, L.
Gross, R.
Powiązania:
https://bibliotekanauki.pl/articles/2037043.pdf
Data publikacji:
2004
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.-y
75.50.Cc
75.50.Ss
Opis:
The magnetic double perovskite materials of composition A$\text{}_{2}$BB'O$\text{}_{6}$ with A an alkaline earth ion and B and B' a magnetic and non-magnetic transition metal or lanthanide ion, respectively, have attracted considerable attention due to their interesting magnetic properties ranging from antiferromagnetism to geometrically frustrated spin systems and ferromagnetism. With respect to application in spin electronics, the ferromagnetic double perovskites with BB'= CrW, CrRe, FeMo, or FeRe and A = Ca, Ba, Sr are highly interesting due to their in most cases high Curie temperatures well above room temperature and their half-metallic behavior. Here, we summarize the structural, magnetotransport, magnetic, and optical properties of the ferromagnetic double perovskites and discuss the underlying physics. In particular, we discuss the impact of steric effects resulting in a distorted perovskite structure, doping effects obtained by a partial replacing of the divalent alkaline earth ions on the A site by a trivalent lanthanide as well as B/B' cationic disorder on the Curie temperature T$\text{}_{C}$, the saturation magnetization and the magnetotransport properties. Our results support the presence of a kinetic energy driven mechanism in the ferromagnetic double perovskites, where ferromagnetism is stabilized by a hybridization of states of the non-magnetic B'-site positioned in between the high spin B-sites.
Źródło:
Acta Physica Polonica A; 2004, 105, 1-2; 7-26
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Phase Diagram of Zinc-Blende Cd$\text{}_{1-x}$Mn$\text{}_{x}$Se
Autorzy:
Sawicki, M.
Furdyna, J. K.
Luo, H.
Powiązania:
https://bibliotekanauki.pl/articles/1952079.pdf
Data publikacji:
1996-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.-y
75.50.Rr
75.50.Lk
Opis:
The paper reports first magnetic measurements performed on MBE grown epilayers of zinc-blende Cd$\text{}_{1-x}$Mn$\text{}_{x}$Se. For all samples studied in the concentration range 0.24 < x < 0.63 we find at low temperatures a history-dependent magnetic response, suggesting a transition to a spin-glass-like state. The central result of the paper is the presentation of a new, complete magnetic phase diagram for this material.
Źródło:
Acta Physica Polonica A; 1996, 90, 5; 923-926
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Al and Cu Additions on Microstructure and Magnetic Properties of NdTb-FeCo-B Magnets
Autorzy:
Sadullahoğlu, G.
Altuncevahir, B.
Addemir, O.
Powiązania:
https://bibliotekanauki.pl/articles/1365124.pdf
Data publikacji:
2014-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Ww
75.50.Vv
75.50.Bb
Opis:
With the addition of Al and/or Cu into the NdFeB based magnet, the soft free iron phase was not observed in the cast alloys while it exists in the microstructure of the undoped NdFeB ingots. For the undoped sample, free iron disappeared after hot deformation process. Grain orientation is not good and there are deviations in the growth direction of the lamellar grains which are not perpendicular to the pressing direction. On the other hand, there is a striking change that the intergranular chemistry of Al added ingot separated into Nd-rich phase and a ternary FeNdAl composition most probably formed at the pressing temperature of 750°C. The highest remanent magnetization of 7.47 kG obtained for this sample, it might be due to the hard magnetic properties of this ternary composition. For the Al-Cu added sample, the high $H_{c}$ and $B_{r}$ values of 7.71 kOe and 7.33 kG, respectively, can be attributed to the homogeneous distribution of the intergranular composition and good orientation of the magnetic grains by hot deformation process.
Źródło:
Acta Physica Polonica A; 2014, 125, 5; 1172-1175
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Search for Dimensionality Crossover of Spin-Glass Freezing in Superlattices of Cd$\text{}_{0.50}$Mn$\text{}_{0.50}$Te/CdTe
Autorzy:
Sawicki, M.
Dietl, T.
Karczewski, G.
Wojtowicz, T.
Kossut, J.
Skośkiewicz, T.
Powiązania:
https://bibliotekanauki.pl/articles/1952078.pdf
Data publikacji:
1996-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.-y
75.50.Rr
75.50.Lk
Opis:
SQUID measurements of the time decay of the thermoremanent magnetization (field-cooled in 1000 Oe) at long time scale, 10$\text{}^{2}$ < t < 10$\text{}^{5}$ s, are presented for MBE grown Cd$\text{}_{0.50}$Mn$\text{}_{0.50}$Te. We found that for both thin (32 Å) and thick (2500 Å) layers the spin-glass dynamics is characterized by a similar value of k = -(1/T$\text{}_{f}$)(dT$\text{}_{f}$/dlogt) > 0.05, indicating the absence of the phase transition at nonzero temperature under the experimental conditions.
Źródło:
Acta Physica Polonica A; 1996, 90, 5; 919-922
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Characterization of Molecular Beam Epitaxy Grown $Cd_{1-x}$Mn$\text{}_{x}$Te Structures
Autorzy:
Sawicki, M.
Kolesnik, S.
Wojtowicz, T.
Karczewski, G.
Janik, E.
Kutrowski, M.
Żakrzewski, A.
Dynowska, E.
Dietl, T.
Kossut, J.
Powiązania:
https://bibliotekanauki.pl/articles/1931934.pdf
Data publikacji:
1995-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.-y
75.50.Rr
75.50.Ee
Opis:
The paper reports on the application of SQUID magnetometry to probe magnetic ion distribution in epilayers and at interfaces of diluted magnetic semiconductors. We present also new results on the possible influence of the magnetic confinement on the formation of the spin-glass phase, and on antiferromagnetic phase transition in zinc-blende MnTe.
Źródło:
Acta Physica Polonica A; 1995, 87, 1; 169-172
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of Grain Boundary Compositions and Magnetic Properties of Hot-Worked $Nd_{18}Tb_1Fe_{66.5}Co_5Al_{1.5}B_8$ Magnets
Autorzy:
Sadullahoğlu, G.
Altuncevahir, B.
Okan Addemir, A.
Powiązania:
https://bibliotekanauki.pl/articles/1399702.pdf
Data publikacji:
2013-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Ww
75.50.Vv
75.50.Bb
Opis:
Magnetic properties which are related to the compositions on the grain boundaries of the NdFeB permanent magnets were studied at different hot working temperatures applied to the cast $Nd_{18}Tb_1Fe_{66.5}Co_5Al_{1.5}B_8$ ingots. Since the addition of Al caused the formation of hard magnetic μ phase between the magnetic NdFeB crystals after the pressing 800C $H_{c}$ value increased to the highest value of 8.21 kOe. According to the SEM micrographs and EDS analysis, the increase in pressing temperature, the atomic ratios in the NdFeAl compositions approached to hard magnetic μ phase with the increase in pressing temperature and its exact composition was obtained in the sample hot deformed at 800°C. Although the secondary μ phase with a high melting temperature is detremental to the alignment of c axis of the magnetic NdFeB grains along the pressing direction, we found that the magnetic properties of the magnets improve due to the presence of this hard magnetic phase on the grain boundaries.
Źródło:
Acta Physica Polonica A; 2013, 123, 2; 233-234
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties of Transition Metal Molybdates
Autorzy:
Konieczny, P.
Pełka, R.
Grzesiak-Nowak, M.
Szymańska, A.
Łasocha, W.
Wasiutyński, T.
Powiązania:
https://bibliotekanauki.pl/articles/1368631.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Xx
75.50.Ee
75.50.-y
Opis:
Two examples of transition metal molybdates were studied with the use of X-ray diffraction and DC magnetometry techniques. First compound, copper dimolybdate trihydrate $CuMo_{2}O_{7}$·$3H_{2}O$ contains 2D layers. The second one is fibrillar cobalt trimolybdate octahydrate $CoMo_{3}O_{10}$·$8H_{2}O$. Both compounds exhibit paramagnetic behaviour at room temperature. However, in the first one copper ions form dimers linked by oxygen bridges, in which exchange interactions between two localized spin states occur. The second compound consists of isolated cobalt ions in the octahedral surroundings, resulting in magnetic properties deviating from the Curie law.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 250-251
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
X-ray Reflectivity and Polarized Neutron Reflectivity Investigations of $[Co_{60}Fe_{60}B_{20}//MgO]_n$ Multilayers
Autorzy:
Vadalà, M.
Wolff, M.
Westerholt, K.
Zabel, H.
Wisniowski, P.
Cardoso, S.
Powiązania:
https://bibliotekanauki.pl/articles/1814030.pdf
Data publikacji:
2007-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.-i
75.50.Kj
75.50.Cc
Opis:
In recent years magnetic tunnel junctions have been intensively studied and incorporated in magnetic random access memory devices and magnetic sensors, where large tunnelling magnetoresistance ratios are preferred. The largest tunnelling magnetoresistance values until now have been observed in magnetic tunnel junctions with MgO barriers and CoFeB electrodes after annealing of the junction above the recrystallization temperature of the amorphous CoFeB layers. We used X-ray reflectivity and polarized neutron reflectivity to study [Co_{60}Fe_{60}B_ {20}//MgO]_{x14} multilayers with the MgO layers prepared by different methods and annealed at different temperatures in order to compare the interface quality and the structural changes induced upon annealing.
Źródło:
Acta Physica Polonica A; 2007, 112, 6; 1249-1257
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetization Reversal Processes in Pr-Fe-B-type Nanocrystalline Magnets
Autorzy:
Pawlik, K.
Pawlik, P.
Kaszuwara, W.
Wysłocki, J.
Powiązania:
https://bibliotekanauki.pl/articles/1368000.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Vv
75.60.Ej
75.50.Bb
75.50.Tt
75.50.Ww
Opis:
The magnetization reversal processes in magnets derived from rapidly solidified $Pr_{9}Fe_{52}Co_{13}Zr_{1}Nb_{4}B_{21}$ alloy samples were studied by analysis of minor hysteresis loops and recoil curves. The studies were carried out on suction-cast 1 mm diameter rod, 1 mm thick plate, 3 mm outer diameter (o.d.) tube and melt-spun ribbon samples subjected to annealing at 983 K for 5 min. The X-ray diffraction analysis has shown multiphase constitution of the samples. Structural and magnetic studies indicated that the initial state of microstructure and phase composition affects the magnetization reversal processes in annealed samples due to a variation of microstructure in samples of various shapes. Magnetic studies allowed estimation of the mean values of nucleation and pinning fields that control the magnetization reversal processes.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 186-187
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High-Coercivity FePt Nanoparticle Assemblies Embedded in Oxide-Matrix by Atomic Layer Deposition
Autorzy:
Kong, J.
Li, A.
Gao, M.
Yan, Q.
Wu, D.
Powiązania:
https://bibliotekanauki.pl/articles/1399662.pdf
Data publikacji:
2013-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Vv
75.75.Cd
75.50.Bb
75.50.Ss
Opis:
Self-assembled face-centered cubic FePt nanoparticles were embedded into the oxide capping layer using the atomic layer deposition technology. The effect of the oxide-matrix layer on the structure, mono-dispersibility, and magnetic properties of the FePt/oxide composite thin films was investigated. Experimental results suggest that the protection of the oxide-matrix capping layer can effectively inhibit the grain growth and particle aggregation, and preserve the ordered domains of the FePt nanoparticles during the L 1_0 ordering transition through annealing. The combination of the atomic layer deposition capping layer and self-assembled FePt nanoparticles provides a new potential approach to fabricate the ultrahigh-density magnetic recording media.
Źródło:
Acta Physica Polonica A; 2013, 123, 2; 173-176
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal Compensation Model of Magnetic Circuits with Modern Magnetic Materials
Autorzy:
Szumiata, T.
Gzik-Szumiata, M.
Powiązania:
https://bibliotekanauki.pl/articles/1388066.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Ww
75.50.Vv
75.50.Kj
75.50.Bb
07.55.Db
Opis:
In this work a quantitative analysis of thermal compensation has been performed for a magnetic circuit producing magnetic field in the air gap. The considered system consists of Sm₃Co₁₇ type permanent magnet (as a source of magnetic field), nanocrystalline FINEMET alloy (as ultra-soft magnetic medium) and Fe-Ni low Curie temperature compensative material (as a magnetic shunt). Distribution of magnetic field induction in the circuit has been calculated numerically within standard one-dimensional approximation, considering nonlinearities of compensative material as well as demagnetization susceptibility of permanent magnet. It has been theoretically predicted, that an appropriate choice of the compensative element thickness improves significantly thermal stability of magnetic field in the air gap.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 650-652
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Relaxation and Memory Effect in Nickel-Chromium Cyanide Nanoparticles
Autorzy:
Zentko, A.
Kavečanský, V.
Mihalik, M.
Maťaš, S.
Mitróová, Z.
Zentková, M.
Maryško, M.
Jagličić, Z.
Powiązania:
https://bibliotekanauki.pl/articles/1813858.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Tt
75.50.Lk
Opis:
The low temperature dynamics of a magnetic nanoparticle system $Ni_3[Cr(CN)_6]_2$ with an average nanoparticles size of 4 nm was studied. Using different temperature and field protocols memory phenomena were studied by the DC magnetization and magnetic relaxation measurements of the system at temperatures below $T_m$ = 19 K. Aging experiments show an absence of any waiting time dependence in the magnetization relaxation due to a field change after zero field and field cooling. This observation discriminates the dynamics of the system from the behaviour of a classical spin-glass.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 511-514
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:
Magnetic Specific Heat Study of the Competition between Ferro- and Antiferromagnetic Spin-Spin exchange Interactions in PbSnMnTe
Autorzy:
Łazarczyk, P.
Jędrzejczak, A.
Story, T.
Arciszewska, M.
Gałązka, R. R.
Powiązania:
https://bibliotekanauki.pl/articles/1952041.pdf
Data publikacji:
1996-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
75.50.Lk
Opis:
Magnetic contribution to the specific heat, magnetic susceptibility and Hall effect are experimentally studied in Pb$\text{}_{1-x-y}$Sn$\text{}_{y}$Mn$\text{}_{x}$Te semimagnetic semiconductors with y=0.72 and x=0.08 and with different carrier concentrations 10$\text{}^{20}$ ≤ p ≤ 10$\text{}^{21}$ cm$\text{}^{-3}$. The ferromagnetism observed in crystals with p ≥ 3×10$\text{}^{20}$ cm$\text{}^{-3}$ breaks down with a decreasing concentration of carriers due to an increasing competition between Ruderman-Kittel-Kasuya-Yoshida and superexchange interactions.
Źródło:
Acta Physica Polonica A; 1996, 90, 5; 891-894
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Vanadium Substitution of Cobalt in $NdCo_2Si_2$
Autorzy:
Chowdhury, R.
Dhara, S.
Bandyopadhyay, B.
Powiązania:
https://bibliotekanauki.pl/articles/1402070.pdf
Data publikacji:
2015-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.Lp
75.50.Gg
75.50.Ee
75.50.Cc
75.50.Dd
Opis:
In NdCo₂Si₂, partial substitution of Co by V having a larger atomic radius results in negative pressure affecting the magnetic properties of the compound. The samples $Nd(Co_{1-x}V_{x})_Si_2$ (x=0, 0.20, 0.35) have been prepared and characterized using X-ray diffraction. The parent compound NdCo₂Si₂ is antiferromagnetic with $T_{N}$ of 34 K whereas the temperature dependence of inverse susceptibility in the doped samples show ferrimagnetic behaviour below 45 K. From the magnetic field dependence of magnetization and the coercive fields obtained from hysteresis loops, the doped samples exhibit ferromagnetism below ≈ 20 K. The specific heat studies compare the magnetic transitions in the parent and doped samples. $Nd(Co_{0.65}V_{0.35})_2Si_2$ shows a magnetoresistance of 15% at 4 K.
Źródło:
Acta Physica Polonica A; 2015, 128, 4; 530-532
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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