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Tytuł:
Effect of Adding of V and Co Atoms on the Spin Glass Transition Temperature of Fe$\text{}_{0.7-x}$M$\text{}_{x}$Al$\text{}_{0.30}$ Alloys
Autorzy:
Azez, K. A.
Powiązania:
https://bibliotekanauki.pl/articles/2035747.pdf
Data publikacji:
2003-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Bb
Opis:
Magnetization measurements on zero field cooled (M$\text{}_{ZFC}$) and field cooled (M$\text{}_{FC}$) with temperature T were made on Fe$\text{}_{0.7-x}$M$\text{}_{x}$Al$\text{}_{0.30}$ alloys (where M = Co or M = V). Compared to Co and V free alloy Fe$\text{}_{0.7}$Al$\text{}_{0.30}$, our results revealed that an addition of small amount of M = Co with 0≤ x≤0.10 shows linear decrease in the transition temperature T$\text{}_{f}$ as x increases. Addition of small amount of M = V with 0≤ x≤0.1 shows gradual decrease in T$\text{}_{f}$ with increasing x. The relative changes in T$\text{}_{f}$ show that an addition of V atoms is of more significance than addition of Co atoms. There is a twofold decrease which could be attributed to the ferromagnetic nature of Co atoms and to the random fields.
Źródło:
Acta Physica Polonica A; 2003, 103, 5; 471-476
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Light Polarization on Reorientation Nonlinearity in Nematic Liquid Crystals
Autorzy:
Brzdąkiewicz, K. A.
Karpierz, M. A.
Powiązania:
https://bibliotekanauki.pl/articles/2035686.pdf
Data publikacji:
2003
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.65.-k
42.70.Df
Opis:
Nematic liquid crystals are characterized by a giant optical nonlinearity which has its origin in the molecular reorientational phenomenon. Uniqueness of this nonlinear mechanism causes that response of the medium is dependent on many conditions. Among various circumstances, both an initial alignment of liquid crystal cell and geometry of the system are very important, but in this paper a significant role of light polarization in nonlinear effects observed in nematics is emphasized. Additionally, it is underlined that dependence on light polarization does not have only trivial aspect of initial conditions. More complex seems to be the fact that due to the high optical anisotropy of the medium the state of light polarization is changing on the way of beam propagation. As a consequence, the modifications of molecular orientation in the liquid crystal cell are strongly dependent upon light polarization.
Źródło:
Acta Physica Polonica A; 2003, 103, 2-3; 195-205
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Screening on Resistivity of Liquid Metals
Autorzy:
Azez, K. A.
Al-Omari, I. A.
Powiązania:
https://bibliotekanauki.pl/articles/1967895.pdf
Data publikacji:
1997-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.15.Cz
Opis:
Calculations of the resistivity of liquid metals are performed basing on the structure factor a(q) which can be measured experimentally or calculated theoretically from the hard sphere model. The calculations are carried out by using the Ashcroft empty core pseudopotential in the framework of Ziman's formula along with different forms of the screening function due to Hartree, Geldart and Vosko, Hubbard, Overhauser, random phase approximation and self-consistent screening. The investigation is useful because it throws light on the importance of exchange and correlation effects in developing an appropriate description of the screening of ions by conduction electrons for calculating the resistivity of liquid metals.
Źródło:
Acta Physica Polonica A; 1997, 92, 3; 563-568
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modeling of Spatial Solitons in Twisted Nematics Waveguides
Autorzy:
Karpierz, M. A.
Brzdąkiewicz, K. A.
Nguyen, Q. V.
Powiązania:
https://bibliotekanauki.pl/articles/2035666.pdf
Data publikacji:
2003
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.65.Wi
42.70.Df
Opis:
Theoretical analysis of light beam propagation in twisted nematic liquid crystalline waveguides is presented. Due to the optical reorientation nonlinearity, the light beam changes the direction of propagation and optical spatial soliton is formed. Modeling of such behavior is presented by using (2+1)-dimensional vector beam propagation method as well as simplified (1+1)-dimensional method. Although both approaches give similar results, the differences are discussed in detail.
Źródło:
Acta Physica Polonica A; 2003, 103, 2-3; 169-175
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties of DyTe
Autorzy:
Pokrzywnicki, S.
Duczmal, M.
Pawlak, L.
Nenkov, K. A.
Powiązania:
https://bibliotekanauki.pl/articles/1964659.pdf
Data publikacji:
1997-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Ee
75.30.Cr
Opis:
Dysprosium monotelluride is a metallic substance with one valence electron per formula unit belonging to the conduction band. It crystallizes in the defected NaCl-type structure (a= 0.6070 nm) with cation deficiency in the metal sublattice. AC and DC susceptibilities exhibit a maximum at 15 K and a second maximum at higher temperatures which position is field dependent.
Źródło:
Acta Physica Polonica A; 1997, 92, 2; 351-354
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic-Form Factor Measurements by Polarised Neutron Scattering: Application to Heavy Fermion Superconductors
Autorzy:
Neumann, K.-U.
Ziebeck, K. R. A.
Powiązania:
https://bibliotekanauki.pl/articles/1929383.pdf
Data publikacji:
1993-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.25.+z
71.28.+d
Opis:
The experimental technique of spin polarised neutron scattering as used in magnetic form factor measurements is presented. An introduction to the interpretation and the calculation of magnetic form factors and magnetization densities is given. The experimental technique of neutron scattering theory as applied to elastic spin polarised scattering experiments is briefly introduced. The calculation of the magnetic form factor and the magnetization densities are considered for simple model systems such as a collection of localised magnetic moments or an itinerant electron system. The discussion is illustrated by an experimental investigation of the magnetic form factor in the heavy fermion superconductors UBe$\text{}_{13}$ and UPt$\text{}_{3}$. Magnetization density maps and magnetic form factors are presented, and their implications for other physical quantities are briefly discussed.
Źródło:
Acta Physica Polonica A; 1993, 84, 1; 43-81
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structure of an Al-Fe-Ni Decagonal Quasicrystal Studied by Cs-Corrected STEM
Autorzy:
Yasuhara, A.
Yamamoto, K.
Yubuta, K.
Hiraga, K.
Powiązania:
https://bibliotekanauki.pl/articles/1373700.pdf
Data publikacji:
2014-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.66.-f
Opis:
The structure of an Al-Fe-Ni decagonal quasicrystal with two quasiperiodic planes along the periodic axis in an $Al_{72}Ni_{24}Fe_4$ alloy has been examined by spherical aberration (Cs)-corrected scanning transmission electron microscopy with high-angle annular dark-field and annular bright-field techniques. The transition-metal atoms and mixed sites (MSs) of Al and transition-metal atoms are represented as separated bright dots in the observed high-angle annular dark-field scanning transmission electron microscopy images, and consequently the arrangements of transition-metal atoms and mixed sites on the two quasiperiodic planes can be directly determined. The transition-metal atoms are arranged on a pentagonal tiling of an edge-length of 0.76 nm. The close examination of observed annular bright-field- and high-angle annular dark-field scanning transmission electron microscopy images indicates the existence of large decagonal columnar clusters with 3.2 nm diameter, and their arrangement on pentagonal, thin rhombic and squashed hexagonal tiles with an edge-length of 3.2 nm. The arrangements of transition-metal atoms in these three tiles are placed on an ideal pentagonal tiling with an edge-length of 3.2 nm, which is generated by the projection of a five-dimensional hyper-cubic lattice. The vertices are denoted by 5D hyper-cubic indices and then they are projected on the occupation domains in perpendicular space. The arrangement of Al atoms as well as transition-metal atoms and mixed sites in the large decagonal atom cluster with about 3.2 nm diameter is interpreted from the observed high-angle annular dark-field- and annular bright-field scanning transmission electron microscopy ABF-STEM images.
Źródło:
Acta Physica Polonica A; 2014, 126, 2; 637-640
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of Al/Steel Bimetal Composite Fabrication by Vacuum Assisted Solid Mould Investment Casting
Autorzy:
Guler, K.
Kisasoz, A.
Karaaslan, A.
Powiązania:
https://bibliotekanauki.pl/articles/1377846.pdf
Data publikacji:
2014-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.30.Fb
81.30.-t
81.20.-n
Opis:
Bimetal composites are a group of promising engineering materials with high developing and service potential. Especially in many fields they can be a powerful low cost alternative to metal-ceramic composites. The most commonly encountered type of these composites is steel reinforced aluminium matrix composites which stand out with high wear and abrasion resistance. Significant fabrication processes of metal/metal composites are based on liquid metal techniques. In this study, Al/steel composite specimens were produced by using vacuum assisted solid mould investment casting technique. A7075 wrought aluminium alloy were infiltrated into steel preforms, which were produced with 304 stainless steel and H13 hot-work tool steel turnings, in the plaster based solid investment casting moulds. Microstructure observations, HV microhardness measurements, scanning electron microscopy and energy dispersive X-ray spectroscopy analysis were carried out for characterization.
Źródło:
Acta Physica Polonica A; 2014, 126, 6; 1327-1330
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the Neglect of Local Coulomb Interaction on Oxygens in Perovskites Described by the Multiband d-p Model
Autorzy:
Rościszewski, K.
Oleś, A.
Powiązania:
https://bibliotekanauki.pl/articles/1029759.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.15.-m
75.25.Dk
75.47.Lx
Opis:
On the example of TiO₄ layer (such as realized in Sr₂TiO₄) we study electronic structure of multiband d-p models describing transition metal perovskites. As suggested by experiment, the studied system is predicted to be a robust nonmagnetic insulator. A realistic treatment of electronic structure requires one to introduce non-zero Coulomb local interactions at 2p oxygen orbitals. However, up till now majority of papers based upon multiband models made an approximation of neglecting such interactions. We show that this simplification does not lead to serious problems in predictions of the electronic structure provided the Coulomb interactions at titanium ions and charge transfer gap are suitably renormalized (so they become entirely different with respect to the true microscopic d-p model parameters).
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 356-358
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of yttria on the phase formation and sintering of HA-Al₂O₃ biocomposites
Autorzy:
Öksüz, K.
Özer, A.
Powiązania:
https://bibliotekanauki.pl/articles/1057899.pdf
Data publikacji:
2017-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
87.85.J-
87.85.jj
81.07.-b
88.30.mj
87.85.Lf
Opis:
Hydroxyapatite is very-well known as the main component of hard tissues and, as such, it has attracted much attention by researchers in the recent decades. This study was aimed to present the characterization of Y₂O₃ doped 50 wt.% hydroxyapatite - 50 wt.% Al₂O₃ composite materials fabricated at relatively high temperature of 1600°C. Hydroxyapatite powder was obtained from bovine bones via calcination and ball milling technique. Fine powders ( ≤ 1 μm) of hydroxyapatite/Al₂O₃ were admixed with 0.5 and 1 wt.% Y₂O₃ powders. Powder compacts were sintered at 1600°C for 4 h in air atmosphere. The field emission scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffraction studies following the relative density measurements were conducted. Moreover, the microhardness was studied as the mechanical property of sintered samples. The effect of increasing Y₂O₃ content on surface morphology, elemental distribution and phase evaluation was investigated in hydroxyapatite/Al₂O₃ biocomposite materials. It was found that by increasing Y₂O₃ content, the relative density increased up to 98.8%, while the hardness increased to 863 HV_{(0.2)}. The main phases, which were found, are Hibonite - CaO(Al₂O₃)₆ and beta-tricalcium phosphate - Ca₃(PO₄)₂, according to X-ray diffraction pattern.
Źródło:
Acta Physica Polonica A; 2017, 131, 3; 576-579
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Inter-Orbital Effects in the Impure Pnictide Superconductors
Autorzy:
Ciechan, A.
Wysokiński, K.
Powiązania:
https://bibliotekanauki.pl/articles/1537057.pdf
Data publikacji:
2010-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.Fd
74.20.-z
74.81.-g
Opis:
We study the local properties of the iron oxypnictides by means of the real space Bogolubov-de Gennes equations. Starting with the realistic energy spectrum and assuming small amount of impurities we calculate the energy dependence of the local density of states and spatial distribution of the local values of the superconducting energy gap. We pay particular attention to the role of the inter-orbital scattering of pairs and the effect of impurity scattering on the superconducting state. The effect of inter-orbital impurities depends on the relative signs of the order parameters related to two orbitals in question. For opposite signs impurities produce bound states inside the gap, while for the same sign of the order parameters they hardly affect the superconductor. The results obtained for impure systems have been shown as maps of the order parameters and local density of states. They well compare with the existing scanning tunnelling microscopy spectra of the iron pnictides.
Źródło:
Acta Physica Polonica A; 2010, 118, 2; 356-359
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis of Endogenous Compounds Labeled with $\text{}^{11}C$ for Positron Emission Tomography
Autorzy:
Kilian, K.
Pękal, A.
Powiązania:
https://bibliotekanauki.pl/articles/1402613.pdf
Data publikacji:
2015-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
87.57.un
Opis:
Among the β⁺ emitting isotopes, produced in medical cyclotrons, carbon-11 is promising radionuclide for labeling of biologically active compounds and tracking their distribution in living organism. Therefore aminoacids, carboxylic acids, fatty acids and amines have been widely used in assessing and staging of brain tumors ($\text{}^{11}C$-methionine), prostate cancer ($\text{}^{11}C$-choline, $\text{}^{11}C$-acetate) and neurological disorders ($\text{}^{11}C$-labeled neurotransmitters). This paper reviews recent achievements in synthesis of endogenous substances labeled with $\text{}^{11}C$ and presents our experience in $\text{}^{11}C$-methionine synthesis. Proposed protocol is a reliable tool for routine manufacturing in clinical applications and animal studies.
Źródło:
Acta Physica Polonica A; 2015, 127, 5; 1475-1478
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Quantum versus Classical Polarons in a Ferromagnetic $CuO_3$-Like Chain
Autorzy:
Bieniasz, K.
Oleś, A.
Powiązania:
https://bibliotekanauki.pl/articles/1374771.pdf
Data publikacji:
2014-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.10.Di
75.10.Pq
75.50.Dd
79.60.-i
Opis:
We present an exact solution for an itinerant hole added into the oxygen orbitals of a $CuO_{3}$-like ferromagnetic chain. Using the Green function method, the quantum polarons obtained for the Heisenberg SU(2) interaction between localized Cu spins are compared with the polarons in the Ising chain. We find that magnons with large energy are favorable towards quasiparticle existence, even in the case of relatively modest electron-magnon coupling. We observe two quasiparticle states with dispersion ~2t each, which emerge from the incoherent continuum when the exchange coupling J increases. Quantum fluctuations in the spin system modify the incoherent part of the spectrum and change the spectral function qualitatively, beyond the bands derived from the perturbation theory.
Źródło:
Acta Physica Polonica A; 2014, 126, 4a; A-80-A-83
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pairing Correlations around Negative-U Centre in the Two-Band Model
Autorzy:
Ciechan, A.
Wysokiński, K.
Powiązania:
https://bibliotekanauki.pl/articles/1812284.pdf
Data publikacji:
2008-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.-z
74.81.-g
74.90.+n
Opis:
The electron energy spectrum of many superconducting materials is characterised by the presence of few bands at the Fermi level. In some cases the superconducting properties seem to be dominated by single band but in others the many-band approach is essential ingredient of their description. In this paper we shall study the properties of superconducting impurity placed in a non-superconducting medium. We are interested in the evolution of superconducting correlations within non-superconducting 1- or 2-dimensional system, their dependence on the distance from impurity and changes induced by the presence of the second band and interband scattering. We use real space description of the material and Bogolyubov-de Gennes approach to superconductivity.
Źródło:
Acta Physica Polonica A; 2008, 114, 1; 123-127
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Interrelation between the Optical Conductivity and Crystal Field Splitting in Monolayer Manganites
Autorzy:
Rościszewski, K.
Oleś, A.
Powiązania:
https://bibliotekanauki.pl/articles/1810316.pdf
Data publikacji:
2009-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.47.Lx
75.10.Lp
63.20.Pw
Opis:
We introduce an effective model for correlated $e_g$ electrons which reproduces qualitatively the evolution of magnetic order in monolayer manganites when correlated wave functions are used. Here we address recent optical conductivity measurements suggesting that the splitting between the occupied and empty $e_g$ states is very large in $LaSrMnO_4$, contrary to what is expected for the effective model. We argue that no contradiction was found but several simple-minded one-atom-based expectations concerning crystal-field splitting and optical conductivity are in error.
Źródło:
Acta Physica Polonica A; 2009, 115, 1; 107-109
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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