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Wyświetlanie 1-10 z 10
Tytuł:
Anomalous Low Resistivity at Room and Elevated Temperatures of Manganin Alloy Implanted with High Dose Niobium Ions
Autorzy:
Wiśniewski, R.
Wilczyńska, T.
Powiązania:
https://bibliotekanauki.pl/articles/1492783.pdf
Data publikacji:
2011-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.15.Eb
Opis:
The anomalous low resistivity metallic material at room temperature has been discovered. Known high resistive material called manganin in form of 10 μm thick foil was one side implanted with high dose of niobium ions of 2.5 × $10^{17}$ Nb ions/$cm^2$ and then with 2.5 × $10^{13}$ Kr ions/$cm^2$. Before and after implantation procedure investigated manganin foils were temperature treated in 130°C during 100 h. Basic resistance measurements were performed just after implantation observing large decrease of its resistivity. In repeated measurements after long time later (about twelve months), at temperature of 22°C, practically no resistivity was measured. Four-terminal method for resistance measurements was used.
Źródło:
Acta Physica Polonica A; 2011, 120, 6; 1080-1083
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Compressibility of $AgI-Ag_{2}MoO_{4}$ System Measured in Wide Range of Composition
Autorzy:
Wiśniewski, Z.
Wiśniewski, R.
Wilczyńska, T.
Powiązania:
https://bibliotekanauki.pl/articles/1538417.pdf
Data publikacji:
2010-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.43.Er
61.66.Dk
62.50.-p
Opis:
Results of compressibility measurements of $AgI-Ag_{2}MoO_{4}$ materials for different concentrations of AgI were presented. The obtained results were compared with phase diagram and internal structure of material. It was found that observed values of compressibility coefficient can be related to internal structure of investigated material.
Źródło:
Acta Physica Polonica A; 2010, 117, 4; 601-602
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic and Electronic Properties in Series of $GdT_{x}Ga_{4-x}$ Solid Solutions (T = Ni or Cu)
Autorzy:
Wiśniewski, P.
Gorzelniak, R.
Kaczorowski, D.
Powiązania:
https://bibliotekanauki.pl/articles/1385707.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Ee
72.15.-v
72.15.Jf
Opis:
We present results of extensive measurements of magnetic susceptibility, electrical resistance, specific heat and thermoelectric power of two series of solid solutions $GdNi_{x}Ga_{4-x}$ and $GdCu_{x}Ga_{4-x}$, for ranges of doping x from 0.6 to 1 and from 1 to 1.5, respectively. All studied phases display the Curie-Weiss behaviour of magnetic susceptibility and antiferromagnetic ordering at temperatures below 23 K. Substitution of gallium with transition metal atoms has strong influence on Néel temperatures of all studied phases, shifting them by few K, depending on x. Metamagnetic-like anomalies are observed for some compositions. Behaviour of the electrical resistivity reveals metallic nature of all samples. Their magnetic ordering is reflected in low-temperature anomalies of the resistivity and the heat capacity.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 382-384
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of Flux Pinning in Single Crystals and Melt-Textured YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-x}$
Autorzy:
Puźniak, R.
Wiśniewski, A.
Baran, M.
Zhou, L.
Powiązania:
https://bibliotekanauki.pl/articles/2012973.pdf
Data publikacji:
2000-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.60.Ge
74.60.Jg
74.72.Bk
Opis:
Flux pinning properties of single crystals and melt-textured samples of YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-x}$ were studied for external magnetic field oriented parallel and perpendicular to the CuO$\text{}_{2}$ planes (ab-planes). For H ∥ ab vortex behaviour is mainly determined by a very effective intrinsic pinning mechanism. The irreversibility line is located in the region of higher fields and temperatures in comparison with the irreversibility line for H ⊥ ab. In a single crystal for H ⊥ ab, we observed an increase in the critical current density j$\text{}_{c}$ with magnetic field - the so-called "fishtail effect" - in a very broad temperature range. For H ∥ ab, this effect is observed only at temperatures close to T$\text{}_{c}$, when the intrinsic pinning is much weaker.
Źródło:
Acta Physica Polonica A; 2000, 97, 3; 373-376
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Critical Current Limitations and Irradiation Effects in High-Temperature
Autorzy:
Wiśniewski, A.
Puźniak, R.
Baran, M.
Szymczak, H.
Powiązania:
https://bibliotekanauki.pl/articles/1929389.pdf
Data publikacji:
1993-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.60.Ge
74.60.Jg
61.80.Hg
Opis:
The discovery of high-temperature superconductors stimulated many groups of researchers to study properties of these materials. From the basic point of view the most important problem is to clarify the mechanism of high-temperature superconductivity. From the practical point of view the most challenging task is to find mechanisms of strong pinning of the vortices, and thereby to obtain materials with high critical current density. The aim of this paper is to discuss problems connected with critical current limitations and to present possibilities which offer irradiation effects with respect to critical current enhancement.
Źródło:
Acta Physica Polonica A; 1993, 84, 1; 139-164
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structure and Superconductivity of $FeSe_{1 - x}$ and $FeTe_{1 - y}Se_{y}$ Crystals: Dependence on the Synthesis Methods, Starting Composition, and Growth Conditions
Autorzy:
Gawryluk, D.
Fink-Finowicki, J.
Wiśniewski, A.
Puźniak, R.
Domukhovski, V.
Diduszko, R.
Berkowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/1537007.pdf
Data publikacji:
2010-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.05.cp
74.25.Ha
74.62.Bf
74.70.Xa
81.10.Fq
Opis:
Syntheses of superconducting iron chalcogenides $FeSe_{1 - x}$ (x = 0-0.15) and $FeTe_{1 - y}Se_{y}$ (y = 0.3-0.55) were performed. Superconducting phase of iron selenide was obtained by the solid-state reaction and from liquid phase. The highest values of critical temperature ($T_c$ = 8.2-8.7 K) exhibit $FeSe_{1-x}$ obtained by the crystallization from a melt with excess of iron less than 1 mol%. The samples from a melt contain up to 78% of tetragonal phase, as estimated by the X-ray diffraction. Lattice parameters and unit cell volume for the samples exhibiting highest $T_{c}$ and sharpest transition to superconducting state are limited to narrow range, with c/a ratio close to 1.469. The samples with excess of selenium contain higher amount of hexagonal phase than stoichiometric one. Superconducting single-crystalline samples of $FeTe_{1 - y}Se_{y}$ (up to 100% of tetragonal phase) were obtained using Bridgman's method. When y value increases, the volume of unit cell decreases. The critical temperature $T_{c}$ changes from ≈ 11.5 K for y ≈ 0.3 to ≈ 14.7 K for y ≈ 0.5.
Źródło:
Acta Physica Polonica A; 2010, 118, 2; 331-335
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Pressure on Magnetic Properties of La$\text{}_{1-x}$ Sr$\text{}_{x}$CoO$\text{}_{3-δ}$(x=0.5, 0.67, 1)
Autorzy:
Piętosa, J.
Wiśniewski, A.
Puźniak, R.
Kolesnik, S.
Majjiga, M.
Dabrowski, B.
Powiązania:
https://bibliotekanauki.pl/articles/2046737.pdf
Data publikacji:
2006-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.-m
75.47.Gk
75.30.Kz
Opis:
Influence of pressure on the phase transition temperature T$\text{}_{C}$ and on the spontaneous magnetisation M$\text{}_{0}$ of highly Sr substituted and oxygen nonstoichiometric La$\text{}_{1-x}$Sr$\text{}_{x}$CoO$\text{}_{3-δ}$ samples was investigated. An increase in T$\text{}_{C}$ and M$\text{}_{0}$ with pressure in investigated samples was found, indicating strengthening of ferromagnetic double exchange interactions, and the expansion of volume of ferromagnetic phase as a~result of enhancement in ferromagnetic interactions in both cluster-glass and long range ferromagnetic states. We did not observe clear correlation between changes in pressure coefficient dT$\text{}_{C}$/dP and changes in the formal oxidation state of the Co ion.
Źródło:
Acta Physica Polonica A; 2006, 109, 4-5; 527-532
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Hydrostatic Pressure on Magnetic Properties of (Sr,La)(Ru,Cr,Mn)O$\text{}_{3}$
Autorzy:
Piętosa, J.
Wiśniewski, A.
Puźniak, R.
Kolesnik, S.
Majjiga, M.
Dabrowski, B.
Powiązania:
https://bibliotekanauki.pl/articles/2047244.pdf
Data publikacji:
2007-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.-m
75.30.Kz
Opis:
An influence of hydrostatic pressure, P, on phase transition temperature, T$\text{}_{C}$, and spontaneous magnetisation, M$\text{}_{0}$, of selected perovskite ruthenates (SrRuO$\text{}_{3}$, La$\text{}_{0.2}$Sr$\text{}_{0.8}$RuO$\text{}_{3}$, SrRu$\text{}_{0.9}$Mn$\text{}_{0.1}$O$\text{}_{3}$, and SrRu$\text{}_{0.9}$Cr$\text{}_{0.1}$O$\text{}_{3}$) was determined to 12 kbar. A decrease in T$\text{}_{C}$ with pressure was found for all of the studied samples. The M$\text{}_{0}$(P) remains unchanged for most of the samples, except for the La$\text{}_{0.2}$Sr$\text{}_{0.8}$RuO$\text{}_{3}$ 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.
Źródło:
Acta Physica Polonica A; 2007, 111, 1; 159-163
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magneto-Optics of Spontaneous and Field Induced Vortices in Twinned YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$/La$\text{}_{1-x}$Sr$\text{}_{x}$MnO$\text{}_{3}$ Bilayers
Autorzy:
Gerbaldo, R.
Ghigo, G.
Gozzelino, L.
Laviano, F.
Mezzetti, E.
Minetti, B.
Przysłupski, P.
Tsarou, A.
Wiśniewski, A.
Powiązania:
https://bibliotekanauki.pl/articles/2047210.pdf
Data publikacji:
2007-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Ha
74.25.Qt
74.78.Db
74.78.Fk
Opis:
The electromagnetic coupling between the magnetic and the superconducting layers in perovskite heterostructures is investigated by means of the magneto-optical technique. The quantitative imaging of the magnetic field distribution allows the high-resolution reconstruction of local supercurrent density. Two phenomena arising from the coupling between manganite layer and the YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$ superconducting film deposited on top are addressed, i.e., the local effects of the electronic coupling between the compounds and the interaction between the manganite magnetic moments and the vortices in the superconductor. The first issue can be quantified in terms of the local superfluid density depression/enhancement in correspondence to the underlying magnetic structure, both domains and domain walls (in dependence on the orientation and sign of the local magnetization) and of the spontaneous, macroscopic screening current loops generated by the manganite domain walls. The interaction between the local manganite magnetization and the superconducting vortices is also influenced by structural defects because they modulate the magnetic pattern of the manganite. Different channelling phenomena in correspondence to the natural twin boundaries of the substrate, but locally magnetized by pinned domain walls of the manganite on their locations, are recognized.
Źródło:
Acta Physica Polonica A; 2007, 111, 1; 47-55
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Relationship between Sample Morphology and Carrier Diffusion Length in GaN Thin Films
Autorzy:
Godlewski, M.
Goldys, E. M.
Phillips, M.
Böttcher, T.
Figge, S.
Hommel, D.
Czernecki, R.
Prystawko, P.
Leszczynski, M.
Perlin, P.
Wisniewski, P.
Suski, T.
Bockowski, M.
Grzegory, I.
Porowski, S.
Powiązania:
https://bibliotekanauki.pl/articles/2035593.pdf
Data publikacji:
2002
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.72.Ff
61.72.Mm
68.37.Hk
78.60.Hk
Opis:
Scanning and spot-mode cathodoluminescence investigations of homo- and hetero-epitaxial GaN films indicate a surprisingly small influence of their microstructure on overall intensity of a light emission. This we explain by a correlation between structural quality of these films and diffusion length of free carriers and excitons. Diffusion length increases with improving structural quality of the samples, which, in turn, enhances the rate of nonradiative recombination on structural defects, such as dislocations.
Źródło:
Acta Physica Polonica A; 2002, 102, 4-5; 627-632
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-10 z 10

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