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Wyświetlanie 1-14 z 14
Tytuł:
Electronic Structure of $Sm(Ni_{1-x}Co_{x})_3$ Alloys - XPS and ab initio Study
Autorzy:
Majtyka, A.
Sikora, M.
Blachiński, D.
Chełkowska, G.
Deniszczyk, J.
Powiązania:
https://bibliotekanauki.pl/articles/1397014.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.Be
79.60.Bm
Opis:
The band structure investigations for $Sm(Ni_{1-x}Co_{x})_3$ alloys by means of X-ray photoelectron spectroscopy (XPS) and an ab initio density functional theory (DFT) calculations are presented. The aim was to determine an effect of Ni/Co substitution on the electronic structure of the alloys. Investigations have shown that the Ni/Co substitution results in a reconstruction of the valence band (VB), especially the intensity near the Fermi level decreases with Co content. An ab initio simulated XPS VB spectra agree qualitatively with experimental ones with the exception of the Sm-4f sub-spectra where the multiplet decomposition is observed. Calculations shown that variation of magnetization in $Sm(Ni_{1-x}Co_{x})_3$ is driven mainly by the Ni/Co-3d and Sm-5d states polarization and increases linearly with rising Co content.
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 673-675
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Fe addition on the martensitic transformation, structure and magnetic properties of metamagnetic Ni-Co-Mn-Sn alloys
Autorzy:
Wójcik, A.
Maziarz, W.
Szczerba, M.
Sikora, M.
Hawełek, Ł.
Czaja, P.
Powiązania:
https://bibliotekanauki.pl/articles/1154400.pdf
Data publikacji:
2016-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
81.30.Kf
Opis:
In this study the effect of Fe for Ni substitution in Ni₄₄Co₆Mn₃₉Sn₁₁ metamagnetic shape memory alloys on their structure, magneto-structural transformation characteristics, magnetic and magnetocaloric properties was studied. The results show that the structure and martensite transformation behavior strongly depends on the Fe concentration. The martensitic transformation temperature decreases with 1 at.% of Fe and is suppressed with higher Fe content. It was further found that substitution of Fe for Ni leads to lowering of the value of magnetic entropy change.
Źródło:
Acta Physica Polonica A; 2016, 130, 4; 1026-1028
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:
An NMR study of Pr$\text{}_{0.5}$Ca$\text{}_{0.5}$Mn$\text{}_{1-x}$Ga$\text{}_{x}$O$\text{}_{3}$ (x=0 and 0.03)
Autorzy:
Oates, C. J.
Kapusta, Cz.
Riedi, P. C.
Sikora, M.
Zając, D.
Rybicki, D.
Martin, C.
Yaicle, C.
Maignan, A.
Powiązania:
https://bibliotekanauki.pl/articles/2037129.pdf
Data publikacji:
2004
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.60.-k
75.47.Gk
Opis:
An NMR study of polycrystalline Pr$\text{}_{0.5}$Ca$\text{}_{0.5}$Mn$\text{}_{1-x}$Ga$\text{}_{x}$O$\text{}_{3}$ (x=0 and 0.03) at 3 K is presented. Zero field spin-echo spectra of the Ga doped compound consist of an overlapping $\text{}^{69,71}$Ga signal at 74~MHz (hyperfine field of 5.3 T), a $\text{}^{55}$Mn double exchange line at 375 MHz (35.5 T) and a weak Mn$\text{}^{3+}$ signal between 400 and 550 MHz. Measurements in an applied field show a step-like increase in the double exchange line intensity, which corresponds to an increase in the amount of the ferromagnetic metallic phase. This coincides with a step-like feature in the bulk magnetization measurements. The effect is similar to that in the previous field dependent $\text{}^{55}$Mn NMR measurements of Pr$\text{}_{0.67}$Ca $\text{}_{0.33}$MnO$\text{}_{3}$. At the demagnetized and remanent state, a variation of spin- spin relaxation time, T$\text{}_{2}$, across the $\text{}^{55}$Mn line, due to the Suhl-Nakamura interaction is observed, which suggests that the ferromagnetic metallic double exchange regions, at liquid helium temperatures, are at least 4 nm in size.
Źródło:
Acta Physica Polonica A; 2004, 105, 1-2; 189-195
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A $\text{}^{55}$Mn NMR Study of La$\text{}_{0.33}$Nd$\text{}_{0.33}$Ca$\text{}_{0.34}$Mn O$\text{}_{3}$ with $\text{}^{16}$O and $\text{}^{18}$O
Autorzy:
Rybicki, D.
Kapusta, Cz.
Riedi, P. C.
Oates, C. J.
Sikora, M.
Zając, D.
De Teresa, J. M.
Marquina, C.
Ibarra, M. R.
Powiązania:
https://bibliotekanauki.pl/articles/2037128.pdf
Data publikacji:
2004
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.60.-k
75.47.Gk
Opis:
A $\text{}^{55}$Mn NMR study of $\text{}^{16}$O and $\text{}^{18}$O containing La$\text{}_{0.33}$Nd$\text{}_{0.33}$Ca$\text{}_{0.34}$Mn O$\text{}_{3}$ is reported. The spin-echo spectra measured at 4.2 K and zero field consist of a double exchange line corresponding to the ferromagnetic metallic regions. The line intensity is more than an order of magnitude lower for the $\text{}^{18}$O compound, which indicates an order of magnitude lower content of the ferromagnetic metallic phase in this compound. The frequency dependence of the spin-spin relaxation time T$\text{}_{2}$ shows a pronounced minimum at the center of the double exchange line of both compounds due to the Suhl-Nakamura interaction, which indicates that the ferromagnetic metallic regions are at least 10~nm in size. The results are discussed in terms of the influence of oxygen isotopic substitution on phase segregation.
Źródło:
Acta Physica Polonica A; 2004, 105, 1-2; 183-188
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
NMR Study of (Sr,Ba,La)$\text{}_{2}$Fe$\text{}_{1+y}$Mo$\text{}_{1-y}$O$\text{}_{6}$ Double Perovskites
Autorzy:
Zając, D.
Kapusta, Cz.
Riedi, P. C.
Sikora, M.
Oates, C. J.
Rybicki, D.
De Teresa, J. M.
Serrate, D.
Marquina, C.
Ibarra, M. R.
Powiązania:
https://bibliotekanauki.pl/articles/2041522.pdf
Data publikacji:
2004-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.25.+z
76.60.-k
78.70.Gq
75.47.Gk
Opis:
The $\text{}^{95}$Mo and $\text{}^{97}$Mo NMR spin-echo study of (Sr,Ba,La)$\text{}_{2}$Fe$\text{}_{1 +y}$Mo$\text{}_{1-y}$O$\text{}_{6}$ double perovskites is reported. Powder samples of Ba$\text{}_{1.44}$Sr$\text{}_{0.36}$La$\text{}_{0.2}$FeMoO$\text{}_{6}$ and (Ba$\text{}_{0.8}$Sr$\text{}_{0.2}$)$\text{}_{2-2x}$La$\text{}_{x}$#$\text{}_{x}$ Fe$\text{}_{1+y}$Mo$\text{}_{1-y}$O$\text{}_{6}$, where# denotes vacancies, for: x=0, y=0; x=0.1, x=0.2 and x=0.3, y=0 and y=0.2 were measured at 4.2 K and no applied magnetic field. NMR signals are observed at 55-100 MHz for the main line and 30-55 MHz for low-frequency satellite. The main line and the satellite are attributed to the ideal and defect positions of Mo atoms. La and vacancy doping introduce more defects, however, increasing the Fe/Mo ratio decreases the amount of defect Mo sites. La doping causes a satellite pattern at the high frequency side of the spectrum, which is related to different numbers of the La next neighbours. The effect is attributed to an increase in the electron density and the corresponding magnetic moment at the adjacent Mo sites and reveals a local character of the electron doping.
Źródło:
Acta Physica Polonica A; 2004, 106, 5; 759-765
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Local Magnetic and Electronic Properties of the A$\text{}_{2}$FeM'O$\text{}_{6}$ (A = Ba, Sr, Ca, M' = Mo, Re) Double Perovskites
Autorzy:
Zając, D.
Sikora, M.
Prochazka, V.
Borowiec, M.
Stępień, J.
Kapusta, Cz.
Riedi, P. C.
Marquina, C.
De Teresa, J. M.
Ibarra, M. R.
Powiązania:
https://bibliotekanauki.pl/articles/2047344.pdf
Data publikacji:
2007-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.-m
76.60.-k
76.60.Jx
78.80.En
Opis:
The results of a combined NMR, X-ray absorption spectroscopy and X-ray magnetic cirrcular dichroism study of the AA'FeMoO$\text{}_{6}$ and AA'FeReO$\text{}_{6}$ double perovskites are presented. They revealed a dependence of electronic and magnetic properties, including a d-electron transfer between Fe and Mo sites, on the structural tolerance factor. The maximum value of the 4d Mo electron occupation and the corresponding Mo moment is obtained for the tolerance factor of unity. This corresponds to the maximum strength of the magnetic interaction and, respectively, to the Curie temperature. The dominant T$\text{}^{5}\text{}^{/}\text{}^{2}$ type temperature dependence of the Mo hyperfine field reveals the half-metallicity of the AA'FeMoO$\text{}_{6}$ compounds. Antisite defects and antiphase boundaries have been identified in NMR measurements and the strength of their magnetic coupling have been determined. A considerable orbital contribution to the Re and Fe magnetic moments were found in the NMR and X-MCD measurements on the AA'FeReO$\text{}_{6}$ compounds. Its magnitude decreases with increasing structural tolerance factor and is correlated with their magnetic anisotropy.
Źródło:
Acta Physica Polonica A; 2007, 111, 6; 797-820
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ordered Phases and Magnetic Excitations in Doped Manganites
Autorzy:
Sikora, O.
Oleś, A.M.
Powiązania:
https://bibliotekanauki.pl/articles/2038394.pdf
Data publikacji:
2004-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.47.Lx
75.30.Ds
75.50.Ee
Opis:
We present theoretical models concerning magnetic and charge ordering in half-doped manganites. The new approach to microscopic description of this group of compounds, taking into consideration the oxygen degrees of freedom, is discussed. The spin wave dispersion relations are shown both in the model of effective spins on Mn ions and in the new approach when two Mn ions form a large effective spin S=7/2.
Źródło:
Acta Physica Polonica A; 2004, 106, 5; 659-664
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nanoscopic Investigation of Magnetic Thin Films by Means of Magnetic Force Microscopy Technique
Autorzy:
Sikora, A.
Ozimek, M.
Wilczyński, W.
Powiązania:
https://bibliotekanauki.pl/articles/1398987.pdf
Data publikacji:
2016-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.15.Cd
68.37.Rt
75.70.Kw
Opis:
In the article the results of the research aimed at the recognition of the correlation between the Ni-Fe film thickness and its magnetic domain structures are described. Magnetic thin films were prepared by pulse magnetron sputtering. Obtained thin film thicknesses were in the range of 47.6-326.0 nm. Magnetic domain structures were imaged using magnetic force microscopy. In order to obtain quantitative description of magnetic domains images, the algorithms designed for topography parameters determination were applied, enabling the comparison of specific factors related to the magnetic properties of the samples. Utilized approach provided the analysis of the impact of sputtering parameters on the morphological and magnetic properties of obtained films.
Źródło:
Acta Physica Polonica A; 2016, 129, 6; 1226-1229
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Copper Deficiency - a Crystallochemical Nature of Ce-Doped Gd$\text{}_{2}$CuO$\text{}_{4}$ Phase. Part II
Autorzy:
Horyń, R.
Bukowska, E.
Sikora, A.
Wołcyrz, M.
Powiązania:
https://bibliotekanauki.pl/articles/2041471.pdf
Data publikacji:
2004-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.75.+g
81.40.Rs
75.50.-y
72.20.My
Opis:
Two samples of nominal composition Gd$\text{}_{1.80}$Ce$\text{}_{0.15}$CuO$\text{}_{4.0}$ and Gd$\text{}_{1.85}$Ce$\text{}_{0.15}$CuO$\text{}_{4.075}$ were subjected for a long-term treatment in air at 1100°C, comprised with a precise control of their weights vs. time of the treatment applied. The gravimetric analysis and the iodometric titration, both showed a deficiency on Cu-site, steadily increasing vs. time with a slight tendency to a saturation. The X-ray analysis of the resulting products showed that even after 272 h of sintering, the samples remained single phase of the "214" structure type. Refinement of their crystal structures as well as density measurements, both allowed confirming Cu deficient structure constitution of these samples. Results of dc-magnetization measurements, performed prior to reduction of the sample's overall oxygen content, did not show any sign of superconductivity down to 4.2 K. These preliminary results indicate that copper deficiency, developing during synthesis, may occur to be a decisive factor for the reported lack of superconductivity in Ce-doped Gd$\text{}_{2}$CuO$\text{}_{4}$ phase. Oxygen content reduction and further tests on the samples obtained are in progress.
Źródło:
Acta Physica Polonica A; 2004, 106, 5; 733-738
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Structures of Ho_5Rh_4Ge_{10}
Autorzy:
Szytuła, A.
Penc, B.
Hofmann, M.
Sikora, W.
Powiązania:
https://bibliotekanauki.pl/articles/1399030.pdf
Data publikacji:
2013-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.25.-j
75.47.Pq
75.50.Ee
Opis:
A powder diffraction measurement of $Ho_5Rh_4Ge_{10}$ is reported. This compound crystallizes in the tetragonal $Sc_5Co_4Si_{10}$-type structure (space group P4/mbm) in which the Ho atoms occupy three different sites. The neutron diffraction measurements indicate antiferromagnetic order with the Néel temperature $T_{N}$=7 K. Below $T_{N}$ an additional phase transition at 4.5 K connected with the change of the magnetic structure is observed. The Ho moments in 4(h) site form collinear order up to T_{N} while moments at 2(a) site form sine modulated structure. Determined experimentally magnetic structures are compared to the results of symmetry analysis.
Źródło:
Acta Physica Polonica A; 2013, 124, 6; 1002-1004
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical, Structural, and Electrical Properties of Aromatic Triphenylamine-Based Poly(azomethine)s in Thin Layers
Autorzy:
Palewicz, M.
Iwan, A.
Sikora, A.
Doskocz, J.
Strek, W.
Sek, D.
Mazurek, B.
Powiązania:
https://bibliotekanauki.pl/articles/1490096.pdf
Data publikacji:
2012-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
77.84.Jd
73.61.Ph
78.66.Qn
Opis:
Spectroscopic and photophysical properties of the poly(azomethine)s with triphenylamine moieties were investigated by UV-vis, X-ray diffraction and atomic force microscopy methods. Current-voltage measurements were performed on ITO/polymer/$Alq_3$/Al, ITO/PEDOT/polymer:MWCNT/Al and ITO/polymer:MWCNT/Al devices. Multiwall carbon nanotubes were blended with polymer in the ratio 1:1. The lowest optical band gap value at 2.33 eV was detected. Moreover, an absorption coefficient α was calculated from transmission and reflectivity measurements. In this paper, we presented photophysical and structural properties of the poly(azomethine)s in solid state of great interest for the emerging field of molecular electronics and for their uses as active layers in (opto)electronic devices such as solar cells.
Źródło:
Acta Physica Polonica A; 2012, 121, 2; 439-444
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Structure of RNiGe and RPdSn Compounds
Autorzy:
André, G.
Bourée, F.
Bombik, A.
Oleś, A.
Sikora, W.
Kolenda, M.
Szytuła, A.
Pacyna, A.
Zygmunt, A.
Powiązania:
https://bibliotekanauki.pl/articles/1929854.pdf
Data publikacji:
1994-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.25.+z
Opis:
Magnetic properties including magnetic structure of ternary RNiGe (R = Tb-Er) and RPdSn (R = Ce, Tb-Ho) compounds are determined. In low temperatures an antiferromagnetic ordering is observed. For compounds with R = Tb-Er the magnetic structure changes with temperature.
Źródło:
Acta Physica Polonica A; 1994, 85, 2; 275-278
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Strategies in Crowd and Crowd Structure
Autorzy:
Gawroński, P.
Malarz, K.
Krawczyk, M.
Malinowski, J.
Kupczak, A.
Sikora, W.
Kułakowski, K.
Wąs, J.
Kantelhardt, J.
Powiązania:
https://bibliotekanauki.pl/articles/1400168.pdf
Data publikacji:
2013-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
02.50.Le
89.65.-s
05.45.-a
Opis:
In an emergency situation, imitation of strategies of neighbours can lead to an order-disorder phase transition, where spatial clusters of pedestrians adopt the same strategy. We assume that there are two strategies, cooperating and competitive, which correspond to a smaller or larger desired velocity. The results of our simulations within the Social Force Model indicate that the ordered phase can be detected as an increase of spatial order of positions of the pedestrians in the crowd.
Źródło:
Acta Physica Polonica A; 2013, 123, 3; 522-525
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-14 z 14

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