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Tytuł:
Femtosecond Optical Breakdown as a Source of the Extreme States of Matter
Autorzy:
Janulewicz, K.
Rehman, Z.
Nguyen, V.
Le, N.
Tran, K.
Grigorov, Y.
Powiązania:
https://bibliotekanauki.pl/articles/1030649.pdf
Data publikacji:
2018-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
79.20.Eb
64.60.A-
47.40.Nm
Opis:
It is well known that from the two fundamental thermodynamic parameters pressure p is much more efficient in transformation of the matter state than temperature T. Optical breakdown in a form of microexplosion proved to be a simple, cheap, and efficient source of transient extreme pressure and temperature. Our interest is focused on the breakdown performed with femstosecond laser pulses both on a surface and in the bulk of material. The paper delivers some examples of the transformation effects observed mostly in the transparent dielectrics under irradiation with femtosecond laser pulses.
Źródło:
Acta Physica Polonica A; 2018, 133, 2; 292-295
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Refurbished Z Facility: Capabilities and Recent Experiments
Autorzy:
Matzen, M.
Atherton, B.
Cuneo, M.
Donovan, G.
Hall, C.
Herrmann, M.
Kiefer, M.
Leeper, R.
Leifeste, G.
Long, F.
Mckee, G.
Mehlhorn, T.
Porter, J.
Schneider, L.
Struve, K.
Stygar, W.
Weinbrecht, E.
Powiązania:
https://bibliotekanauki.pl/articles/1807851.pdf
Data publikacji:
2009-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
52.58.Lq
52.59.Qy
64.60.A-
81.30.Bx
Opis:
The Z Refurbishment Project was completed in September 2007. Prior to the shutdown of the Z facility in July 2006 to install the new hardware, it provided currents of ≤ 20 MA to produce energetic, intense X-ray sources ( ≈1.6 MJ, > 200 TW) for performing high energy density science experiments and to produce high magnetic fields and pressures for performing dynamic material property experiments. The refurbishment project doubled the stored energy within the existing tank structure and replaced older components with modern, conventional technology and systems that were designed to drive both short-pulse Z-pinch implosions and long-pulse dynamic material property experiments. The project goals were to increase the delivered current for additional performance capability, improve overall precision and pulse shape flexibility for better reproducibility and data quality, and provide the capacity to perform more shots. Experiments over the past year have been devoted to bringing the facility up to full operating capabilities and implementing a refurbished suite of diagnostics. In addition, we have enhanced our X-ray backlighting diagnostics through the addition of a two-frame capability to the Z-Beamlet system and the addition of a high power laser (Z-Petawatt). In this paper, we will summarize the changes made to the Z facility, highlight the new capabilities, and discuss the results of some of the early experiments.
Źródło:
Acta Physica Polonica A; 2009, 115, 6; 956-958
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Majority-Vote Model on Scale-Free Hypergraphs
Autorzy:
Gradowski, T.
Krawiecki, A.
Powiązania:
https://bibliotekanauki.pl/articles/1388421.pdf
Data publikacji:
2015-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
89.75.Hc
64.60.Cn
05.10.Ln
05.50.+q
64.60.F-
Opis:
Majority-vote models on scale-free hypergraphs are investigated by means of numerical simulations with different variants of system dynamics. Hypergraphs are generalisations of ordinary graphs in which higher order of social organisation is included by introducing hyperedges corresponding to social groups, connecting more than two nodes. In the models under study, opinions of agents (two-state spins) placed in nodes are updated according to a probabilistic rule with control parameter representing social noise. The probability of a single spin flip depends on the average opinion within only one social group (hyperedge) the agent belongs to. This introduces an intermediate level of social interactions, in contrast with the case of networks, where the opinion of an agent usually depends on the average opinion of all neighbours. In all cases under consideration a second-order phase transition to a state with an uniform opinion was found as a function of the social noise, with the critical value of the control parameter and the critical exponents depending on the hypergraph topology and details of the system dynamics (node or hyperedge update).
Źródło:
Acta Physica Polonica A; 2015, 127, 3A; A-55-A-58
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Competing Interactions on a Cayley Tree-Like Lattice: Pentagonal Chandelier
Autorzy:
Uguz, S.
Ganikhodjaev, N.
Akin, H.
Temir, S.
Powiązania:
https://bibliotekanauki.pl/articles/1490904.pdf
Data publikacji:
2012-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.50.+q
64.60.-i
64.60.De
Opis:
Different types of lattice spin systems with competing interactions have rich and interesting phase diagrams. In this study we present some new results for such systems involving the Ising spin system (i.e. σ = ± 1) using a generalization of the Cayley tree-like lattice approximation. We study the phase diagrams for the Ising model on a Cayley tree-like lattice, a new lattice type called pentagonal chandelier, with competing nearest-neighbor interactions $J_1$, prolonged next-nearest-neighbor interactions $J_{p}$ and one-level next-nearest-neighbor senary interactions $J_{l_1}^{(6)}$. The colored phase diagrams contain some multicritical Lifshitz points that are at nonzero temperature and many modulated new phases. We also investigate the variation of the wave vector with temperature in the modulated phase and the Lyapunov exponent associated with the trajectory of the system.
Źródło:
Acta Physica Polonica A; 2012, 121, 1; 114-118
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of On-Site Coulomb Repulsion on Phase Transitions in Exactly Solved Spin-Electron Model
Autorzy:
Gálisová, L.
Strečka, J.
Tanaka, A.
Verkholyak, T.
Powiązania:
https://bibliotekanauki.pl/articles/1534796.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.50.+q
05.70.Jk
64.60.Cn
64.60.De
Opis:
A hybrid lattice-statistical model on doubly decorated planar lattices, which have localized Ising spins at their nodal lattice sites and two itinerant electrons at each pair of decorating sites, is exactly solved by the use of a generalized decoration-iteration transformation. Our main attention is focused on an influence of the on-site Coulomb repulsion on ground-state properties and critical behavior of the investigated system.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 942-943
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hydrogen Ordering in Hexagonal Intermetallic $AB_5$ Type Compounds
Autorzy:
Sikora, W.
Kuna, A.
Powiązania:
https://bibliotekanauki.pl/articles/1813178.pdf
Data publikacji:
2008-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.60.Cn
Opis:
Intermetallic compounds $AB_5$ type (A = rare-earth atoms, B = transition metal) are known to store reversibly large amounts of hydrogen and as that are discussed in this work. It was shown that the alloy cycling stability can be significantly improved by employing the so-called non-stoichiometric compounds $AB_5+x$ and that is why analysis of change of structure turned out to be interesting. A tendency for ordering of hydrogen atoms is one of the most intriguing problems for the unsaturated hydrides. The symmetry analysis method in the frame of the theory of space group and their representation gives opportunity to find all possible transformations of the parent structure. In this work symmetry analysis method was applied for $AB_5+x$ structure type (P6/mmm parent symmetry space group). There were investigated all possible ordering types and accompanying atom displacements in positions 1a, 2c, 3g (fully occupied in stoichiometric compounds $AB_5$), in positions 2e, 6l (where atom B could appear in non-stoichiometric compounds) and also 4h, 6m, 6k, 12n, 12o, which could be partly occupied by hydrogen as a result of hydrides. An analysis was carried out of all possible structures of lower symmetry, following from P6/mmm for we k=(0, 0, 0). Also the way of getting the structure described by the $P6_3mc$ space group with double cell along the z-axiswe k=(0, 0, 0.5), as it is suggested in the work of Latroche et al. is discussed by the symmetry analysis. The analysis was obtained by computer program MODY. The program calculates the so-called basis vectors of irreducible representations of a given symmetry group, which can be used for calculation of possible ordering modes.
Źródło:
Acta Physica Polonica A; 2008, 113, 4; 1211-1224
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Behaviors of Phase Diagrams of Ising Model with Competing Ternary and Binary Interactions on a Cayley Tree of Arbitrary Order
Autorzy:
Akin, H.
Ganikhodjaev, N.
Uguz, S.
Temir, S.
Powiązania:
https://bibliotekanauki.pl/articles/1490877.pdf
Data publikacji:
2012-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.50.+q
64.60.-i
64.60.De
Opis:
An Ising model with competing interactions has recently been studied extensively because of the appearance of nontrivial magnetic orderings. In this paper, we study the phase diagrams for the Ising model on a Cayley tree with competing nearest-neighbor interactions J and ternary prolonged interactions $J_{t_{p}}$ on a Cayley tree of arbitrary order k and compare with the phase diagrams obtained in Uguz et al. and Vannimenus results for the Ising model on a Cayley tree with competing nearest-neighbor interactions J and ternary prolonged interactions $J_{p}$. For some values of k, we obtain phase diagrams of the model. We clarify the role of order k of the Cayley tree. We also plot the variation of the wave vector with temperature.
Źródło:
Acta Physica Polonica A; 2012, 121, 1; 104-107
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Harmonically Trapped Bosons on the Sierpiński Carpet
Autorzy:
Rovenchak, A.
Powiązania:
https://bibliotekanauki.pl/articles/1535594.pdf
Data publikacji:
2010-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.30.Jp
67.85.-d
64.60.an
Opis:
An ideal Bose-gas confined in a harmonic potential is studied. The thermodynamic properties of the said system are obtained in a general case of D dimensions, where D can be fractional (this corresponds to, e.g., porous medium). For the critical temperature, expansions with respect to the number of particles in the system are obtained. Numerical study is made for D = ln8/ln3 corresponding to the dimensionality of the so-called Sierpiński carpet.
Źródło:
Acta Physica Polonica A; 2010, 118, 4; 531-533
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Asymmetry Driven Phase Transformations
Autorzy:
Damczyk, J.
Ostasiewicz, K.
Radosiński, Ł.
Radosz, A.
Powiązania:
https://bibliotekanauki.pl/articles/1535592.pdf
Data publikacji:
2010-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.70.-a
64.60.-i
63.70.+h
Opis:
Motivated by the properties of one-dimensional lattice systems with asymmetric on-site potential, one can formulate a hypothesis of an asymmetry driven phase transformation. Characteristic feature of one-dimensional systems exhibiting asymmetry driven phase transformation is a sequence of the two phase conversions. In particular class of such systems with a triple-well potential, phase conversions of one-dimensional systems would evolve into a sequence of two phase transitions in three-dimensional models. We propose here a model of three-dimensional system exhibiting a sequence of two first order asymmetry driven phase transitions.
Źródło:
Acta Physica Polonica A; 2010, 118, 4; 527-530
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
NMR Relaxation and ESR Lineshape of Anisotropically Rotating Paramagnetic Molecules
Autorzy:
Kubica, A.
Milewska, A.
Noinska, M.
Earle, K.
Kruk, D.
Powiązania:
https://bibliotekanauki.pl/articles/1490224.pdf
Data publikacji:
2012-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
87.64.kj
87.64.kh
75.10.Dg
76.60.Es
Opis:
The role of anisotropic rotation for electron spin resonance lineshape and nuclear magnetic relaxation dispersion profiles for paramagnetic molecules with electron spin quantum number S ≥ 1 is discussed. The ESR spectra and nuclear magnetic relaxation dispersion profiles are calculated by means of an approach based on the stochastic Liouville equation and referred to in the literature as "Swedish slow motion theory". This description is valid for arbitrary motional conditions and interaction strengths. Molecular tumbling influences the ESR spectra by modulating zero field splitting interactions. The nuclear spin relaxation is affected by the rotational motion in a twofold way: via the electron spin dynamics and as a direct source of modulations of the electron-nuclear dipole-dipole interactions. For coinciding principal axes systems of the permanent (residual, static) zero field splitting and rotational tensors the ESR lineshape is not affected by rotational anisotropy. Rotational anisotropy is important for nuclear relaxation as it is influenced by molecular rotation not only via the electron spin dynamics, but also directly by modulations of the electron spin-nuclear spin dipole-dipole interaction (when the dipole-dipole and zero field splitting frames do not coincide). The anisotropy effects depend strongly on the relative orientation of the dipole-dipole and permanent zero field splitting axes. Nevertheless, a different scenario is also possible. When the diffusion axis coincides with the dipole-dipole axis (but not with the principal axis system of the permanent zero field splitting), the nuclear spin relaxation as well as the ESR lineshape, become sensitive to the rotational anisotropy. The possible dependence of the ESR lineshape and nuclear spin relaxation on the rotational anisotropy should be carefully considered when attempting a joint analysis of ESR and nuclear magnetic relaxation dispersion results for paramagnetic molecules.
Źródło:
Acta Physica Polonica A; 2012, 121, 2; 527-532
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spontaneous Currents in a Bosonic Ring
Autorzy:
Makieła, D.
Maśka, M.
Powiązania:
https://bibliotekanauki.pl/articles/1398603.pdf
Data publikacji:
2016-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
03.75.Lm
03.75.Kk
64.60.Ht
Opis:
Nonequilibrium dynamics of non-interacting bosons in a one-dimensional ring-shaped lattice is studied by means of the kinetic Monte Carlo method. The system is approximated by the classical XY model (the kinetic term is neglected) and then the simulations are performed for the planar classical spins. We study the dynamics that follows a finite-time quench to zero temperature. If the quench is slow enough the system can equilibrate and finally reaches the ground state with uniform spin alignment. However, we show that if the quench is faster than the relaxation rate, the system can get locked in a current-carrying metastable state characterized by a nonzero winding number. We analyze how the zero-temperature state depends on the quench rate.
Źródło:
Acta Physica Polonica A; 2016, 130, 2; 569-572
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mutual Information-Based Hierarchies on Warsaw Stock Exchange
Autorzy:
Fiedor, P.
Powiązania:
https://bibliotekanauki.pl/articles/1388360.pdf
Data publikacji:
2015-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.10.-a
64.60.aq
89.65.-s
89.70.-a
Opis:
A popular method for network analysis of financial markets is a notable part of econophysics research. The networks created in such efforts are focused exclusively on linear correlations between stocks. While Pearson's correlation is the obvious starting point, it would be useful to look at its alternatives as to whether they provide improvements to this methodology, particularly given Pearson's correlation coefficient considers only a limited class of association patterns. We propose to use mutual information-based hierarchical networks, as mutual information is a natural generalisation of Pearson's correlation. We estimate mutual information using naive plug-in estimator as consistent bias is not harmful to this application, however other methods may also be used. We then transform the mutual information into an Euclidean metric and create minimal spanning trees and maximally filtered planar graphs. We apply this methodology to Warsaw Stock Exchange for years between 2000 and 2013, and comment on the differences with the standard methodology, as well as the structural changes on Warsaw Stock Exchange which the study reveals.
Źródło:
Acta Physica Polonica A; 2015, 127, 3A; A-33-A-37
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On Melting of Two-Dimensional Monolayer Films
Autorzy:
Patrykiejew, A.
Zientarski, T.
Binder, K.
Powiązania:
https://bibliotekanauki.pl/articles/1945440.pdf
Data publikacji:
1996-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
82.65.-i
64.60.-i
Opis:
The melting of two-dimensional films formed on the (100) fcc crystal is studied by Monte Carlo simulation. The results obtained suggest that in systems with only weakly corrugated surface potential, exhibiting the hexagonal close packed solid structure, the melting transition is followed by the Ising-type transition as predicted by the theory of Nelson and Halperin. In the case of highly corrugated surface potential, the film forms registered structure which disorders gradually as the temperature is raised.
Źródło:
Acta Physica Polonica A; 1996, 89, 5-6; 735-742
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Phases and Generalized t-J Models in Doped Mott-Hubbard Insulators
Autorzy:
Oleś, A. M.
Zaanen, J.
Powiązania:
https://bibliotekanauki.pl/articles/1861025.pdf
Data publikacji:
1994-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.-h
64.60.-i
64.90.+b
75.40.-s
Opis:
We review some recent results obtained for the dynamics of a single hole and for the ground states at finite hole doping in t-J model. Next, we address the role of orbital degeneracy in doped Mott-Hubbard insulators and show examples of effective strong coupling models which include the orbital degrees of freedom. These new t-J models have interesting phase diagrams, with the new magnetic phases stabilized by a competition between magnetic energy and excitonic excitations. It is argued that the doped holes always bind to the excitons and that the new phases identified on the mean-field level give rise to local distortions of the lattice. We conclude that realistic t-J models derived from the electronic structure of particular compounds may be successfully applied for understanding both the observed magnetic ground states, and the results of photoemission experiments, as we have demonstrated recently for NiO.
Źródło:
Acta Physica Polonica A; 1994, 85, 1; 145-163
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kinetic Analysis of Thermal Processes in Ag-As-S-Se System Based on DSC Measurements
Autorzy:
Čajko, K.
Lukić-Petrović, S.
Štrbac, G.
Ivetić, T.
Powiązania:
https://bibliotekanauki.pl/articles/1398711.pdf
Data publikacji:
2016-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
65.60.+a
64.70.kj
64.70.P-
64.70.kg
Opis:
Thermal properties of glasses from the system $Ag_x(As_{40}S_{30}Se_{30})_{100-x}$ for x=0, 0.5, 1, 3, and 5 at.% were investigated by differential scanning calorimetry. The DSC curves were obtained under non-isothermal conditions which allowed determination of the glass transition temperature $T_{g}$ (onset temperature), crystallization temperature $T_{p}$ (corresponding to the crystallization peak maximum), melting temperature $T_{m}$, crystallization enthalpy $H_{c}$, and melting enthalpy $H_{m}$. The DSC curves obtained at the same heating rate were analyzed in order to study the variation of glass transition temperature with Ag concentration. Observed $T_{g}$ shift toward higher values, with increase in the heating rate, is in agreement with the Lasocka equation. Samples with 3 at.% and 5 at.% Ag were further thermally treated at different heating rates with the aim of analyzing kinetic processes of crystallization. The Moynihan and Kissinger models were used to calculate the activation energy of glass transition and activation energy of crystallization. For the samples that showed the crystallization processes an assessment of the thermal stability was done based on different criteria.
Źródło:
Acta Physica Polonica A; 2016, 129, 4; 509-513
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stripe Phases in the Hubbard Model
Autorzy:
Góra, D.
Rościszewski, K.
Oleś, A. M.
Powiązania:
https://bibliotekanauki.pl/articles/2012901.pdf
Data publikacji:
2000-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.27.+a
74.72.-h
75.10.-b
64.60.-i
Opis:
We investigate the magnetic and charge ordering in the stripe phases obtained while using correlated wave functions for finite 8×8 clusters described by the Hubbard model with extended hopping. Nonmagnetic vertical (01) site-centered domain walls and (11) bond-centered stripes are found for the parameters of La$\text{}_{2-x}$Sr$\text{}_{x}$CuO$\text{}_{4}$ and YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{6+x}$, respectively, at doping δ=1/8. The obtained half-filled domain nonmagnetic walls reproduce the maxima observed in neutron scattering for La$\text{}_{2-x}$Sr$\text{}_{x}$CuO$\text{}_{4}$.
Źródło:
Acta Physica Polonica A; 2000, 97, 1; 225-228
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Applications of Density Matrix Renormalization Group to Problems in Magnetism
Autorzy:
Gehring, G. A.
Bursill, R. J.
Xiang, T.
Powiązania:
https://bibliotekanauki.pl/articles/1953163.pdf
Data publikacji:
1997-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.60.-i
11.10.Gh
Opis:
The application of real space renormalization group methods to quantum lattice models has become a topic of great interest following the development of the density matrix renormalization group by White. This method has been used to find the ground and low-lying excited state energies and wave functions of quantum spin models in which the form of the ground state is not clear, for instance because the interactions are frustrated. It has also been applied to fermion problems where the tendency for localization due to the strong Coulomb repulsion is opposed by the lowering of the kinetic energy which occurs as a result of electron transfer. The approach is particularly suitable for one-, or quasi-one-dimensional problems. The method involves truncating the Hilbert space in a systematic and optimised manner. Results for the ground state energy are thus variational bounds. The results for low-lying energies and correlation functions for one-dimensional systems have unprecedented accuracy and the method has become the method of choice for solving one-dimensional quantum spin problems. We review the method and results obtained for the spin-1 chain with biquadratic exchange as well as the spin-1/2 model with competing nearest and next nearest neighbour exchange will be described. More recently, the density matrix renormalization group has been applied to reformulate the coupling constant renormalization group approach which is appropriate for the study of critical properties. This approach has been applied to the anisotropic spin-1/2 Heisenberg chain. Finally, we discuss recent work which has borne promising applications in two dimensions - the Ising model and the two-dimensional Hubbard model.
Źródło:
Acta Physica Polonica A; 1997, 91, 1; 105-119
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetization and Susceptibility of a Diluted Triangular Ising Antiferromagnet in a Field
Autorzy:
Borovský, M.
Žukovič, M.
Bobák, A.
Powiązania:
https://bibliotekanauki.pl/articles/1199489.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.50.+q
64.60.De
75.10.Hk
75.50.Ee
Opis:
Within the framework of the effective-field theory with correlations we investigate effects of an external magnetic field and random site dilution on basic thermodynamic quantities, such as the magnetization and the magnetic susceptibility, on the geometrically frustrated triangular lattice Ising antiferromagnet. Behavior of these quantities is presented in the temperature-field parameter space for selected mild degrees of dilution. It is found that, besides the anomalies associated with phase transitions from the ferrimagnetic to the paramagnetic state, in certain regions of the parameter space these functions display some more anomalies and peculiarities, as a result of joint effects of the geometrical frustration, magnetic dilution, thermal fluctuations and the applied magnetic field.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 16-17
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Monte Carlo Study of a Periodically Pinned 2D Superconductor
Autorzy:
Rezlescu, N.
Anghelache, R.
Ciobotaru, I.
Powiązania:
https://bibliotekanauki.pl/articles/1955503.pdf
Data publikacji:
1997-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.60.Fr
75.10.Hk
74.25.Bt
Opis:
We show that a natural assumption on the moving mechanism of vortices in a periodically pinned, two-dimensional superconductor in the mixed state is the basis for a n-clock-like model. The pinning points are considered to be centered in each unit cell of the superconducting lattice. This property enables one to use a discrete version of the XY model used in the simulations focusing on the melting of the Abrikosov lattice of vortices in a system of Josephson arrays. A Monte Carlo study performed on the corresponding Hamiltonian in a field given by a filling factor of f=1/2 exhibits two phase transitions, at the temperatures T$\text{}_{c1}$≈0.325 and T$\text{}_{m}$≈0.65. The numerical estimation of the Challa parameters for both transitions indicates their continuous nature. The physical meaning of the lower transition is the expulsion of the magnetic field from the superconducting system, i.e. the Meissner effect. The physical equivalent of the upper transition is the melting of the pinned vortex lattice.
Źródło:
Acta Physica Polonica A; 1997, 91, 2; 337-340
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Low-Temperature Properties of Ising Antiferromagnet on a Stacked Triangular Lattice
Autorzy:
Žukovič, M.
Mižišin, L.
Bobák, A.
Powiązania:
https://bibliotekanauki.pl/articles/1199547.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.50.+q
64.60.De
75.10.Hk
75.50.Ee
Opis:
An Ising antiferromagnet on a stacked triangular lattice in zero field is studied by Monte Carlo simulations, focusing on the character of the low-temperature phase and the effect of the relative strength of the exchange interaction in the stacking direction α. Our results support the presence of the 3D Wannier phase, with the sublattice magnetization structure (m, -m, 0) and power-law decaying m with the lattice size. The extent of this low-temperature phase shrinks with decreasing α, however, it appears even at very low values if it is accessed from higher temperatures by sufficiently slow cooling.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 40-41
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
$\text{}^{57}Fe$ Mössbauer Spectroscopy οf Radiation Damaged Allanites
Autorzy:
Malczewski, D.
Grabias, A.
Powiązania:
https://bibliotekanauki.pl/articles/1811896.pdf
Data publikacji:
2008-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
33.45.+x
61.82.Fd
64.60.My
76.80.+y
Opis:
Metamict minerals contain radioactive elements that degrade the crystal structure of the minerals. The degradation occurs primarily through progressive overlapping recoil nuclei collision cascades from α-decays of $\text{}^{238}U$, $\text{}^{232}Th$, $\text{}^{235}U$ and their daughter products. We report the results of $\text{}^{57}Fe$ Mössbauer spectroscopy, gamma-ray spectrometry and microprobe analysis of three partially metamict allanites, $(Ca,Ce,REE)_2(Fe^{2+},Fe^{3+})$$(Al,Fe^{3+})_2O[Si_2O_7][SiO_4](OH)$ where REE stands for rare earth elements. The samples were collected in pegmatites from Reno, Nevada (USA), Franklin, New Jersey (USA) and Nya Bastnas Field (Sweden). The absorbed α-dose for these minerals was found to range from $5.8×10^{14}$ α-decay/mg for the allanite from Reno to $1.9×10^{15}$ α-decay/mg for the allanite from Franklin. The Mössbauer spectra show a decrease in the $Fe^{2+}$ doublet intensity with increasing absorbed α-dose. We also observe an increase in the line widths of the $Fe^{2+}$ and $Fe^{3+}$ doublets with increasing absorbed α-dose.
Źródło:
Acta Physica Polonica A; 2008, 114, 6; 1683-1690
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of the Introduction of Copper into Amorphous $As_2Se_3$ Matrix on Its Thermal and Structural Characteristics
Autorzy:
Štrbac, G.
Lukić-Petrović, S.
Štrbac, D.
Čajko, K.
Turyanytsa, I.
Powiązania:
https://bibliotekanauki.pl/articles/1399717.pdf
Data publikacji:
2013-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.kj
64.70.P-
65.60.+a
Opis:
This paper describes the results of the determination of some thermal and structural parameters of glasses from the $Cu_{x}(As_2Se_3)_{100-x}$ system for x=0, 1, 5, 10 and 15 at.%. Based on the differential scanning calorimetry curves taken at different heating rates, glass transition temperature $T_{g}$, onset temperature of crystallization $T_{onset}$, and melting temperature $T_{m}$ of crystalline units formed are determined. The values of activation energy $E_{g}$ of glass transition process are calculated. These characteristic temperatures served as the basis for the calculation of the parameters of thermal stability of the glasses towards crystallization.
Źródło:
Acta Physica Polonica A; 2013, 123, 2; 256-258
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study of Glass Transition and Crystallization Behavior in $Ga_{15}Se_{85 - x}Pb_x$ (0 ≤ x ≤ 6) Chalcogenide Glasses
Autorzy:
Khan, Z.
Khan, S.
Alvi, M.
Powiązania:
https://bibliotekanauki.pl/articles/1400308.pdf
Data publikacji:
2013-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.43.Dq
61.05.cp
64.70.p
64.70.dg
65.60.+a
Opis:
There has been a growing interest in the synthesis and characterization of amorphous chalcogenide glasses due to their importance in preparing electronic memories, grating, switching devices and their optical applications as good IR transmitting materials. The study of the glass transformations and crystallization processes in the amorphous systems is interesting not only from the fundamental aspect of establishing the reaction mechanism of crystal nucleation and growth, but also from a technological point of view. The present research work is concentrated on the study of glass transition and crystallization behavior in $Ga_{15}Se_{85 - x}Pb_x$ with x=0, 3, and 6 chalcogenide glasses by differential scanning calorimetry. Their amorphous nature has been verified by X-ray diffraction. The differential scanning calorimetry experiments were performed at different continuous heating rates (5 to 25 K/min). The glass transition temperature (T_{g}) and crystallization temperature $(T_{c})$ of these glasses has been determined from differential scanning calorimetry thermograms. The dependence of $T_{g}$ and $T_{c}$ on the heating rate (β) has been used for the determination of different crystallization parameters such as the activation energy of crystallization (Δ $E_{c}$), the activation energy for structural relaxation (Δ $E_{t}$) and the order parameter (n). The results of crystallization were discussed on the basis of different models such as Kissinger's approach and modification for non-isothermal crystallization in addition to Johnson, Mehl, Ozawa and Avrami.
Źródło:
Acta Physica Polonica A; 2013, 123, 1; 80-86
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Phase Diagrams of Spin-1/2 Ising Model on a Two-Layer Bethe Lattice with AFM/AFM Interactions
Autorzy:
Albayrak, E.
Yigit, A.
Powiązania:
https://bibliotekanauki.pl/articles/1807767.pdf
Data publikacji:
2009-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.50.+q
68.35.Rh
64.60.Cn
Opis:
The phase diagrams of spin-1/2 Ising model on a two-layer Bethe lattice with antiferromagnetic interactions for each layer and either antiferromagnetic or ferromagnetic interaction between the layers are investigated by using the pairwise approach for given values of coordination number q. The exact expressions of the order-parameters, response functions and free energy are obtained in terms of the recursion relations. The ground-state phase diagrams are calculated for given system parameters of the model. In the guidance of the ground-state phase diagrams, the temperature dependent phase diagrams of the model are also studied in detail for given coordination numbers q = 3, 4 and 6. It was found that the system presents only second-order phase transitions with different thermal behaviors for all values of q. In addition, two Néel temperatures, $T_{N}$, are found for q = 6 only.
Źródło:
Acta Physica Polonica A; 2009, 116, 2; 127-134
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermodynamics of Ising Ferromagnet Studied by the Real-Space Renormalization Group Method
Autorzy:
Reich, W.
Piotrkowska, K.
Esposito, U.
Caramico D'Auria, A.
Powiązania:
https://bibliotekanauki.pl/articles/1929558.pdf
Data publikacji:
1993-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.60.Ak
75.40.Cx
Opis:
The critical exponents of the 3D Ising model were calculated in the approximation of the fourth-order cumulant expansion. Thermodynamic functions in the high-temperature range are obtained.
Źródło:
Acta Physica Polonica A; 1993, 84, 2; 275-278
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EPR Study of Monoclinic RbD$\text{}_{2}$PO$\text{}_{4}$ Monocrystal Doped with Cr$\text{}^{5+}$ Ion
Autorzy:
Waplak, S.
Shuvalov, L. A.
Powiązania:
https://bibliotekanauki.pl/articles/1932129.pdf
Data publikacji:
1995-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.-v
64.60.-i
Opis:
Deuterated monoclinic RbD$\text{}_{2}$PO$\text{}_{4}$ (DRDP) doped with chromium Cr$\text{}^{5+}$ is studied by EPR in 90 K to 400 K temperature range. EPR reveals two types of paramagnetic centers: single Cr$\text{}^{5+}$ (S = 1/2) complex and Cr$\text{}^{5+}$-Cr$\text{}^{5+}$ coupled pairs with effective spin S = 1. The EPR line splitting of single Cr$\text{}^{5+}$ complex in DRDP versus temperature agrees with the unit cell multiplication. The splitting of EPR line of pair spectrum appears at T* = 160 K, far below the phase transition temperatures and is due to the anisotropy of the exchange interaction. The clustering effect in the low-dimensional DRDP is suggested.
Źródło:
Acta Physica Polonica A; 1995, 87, 3; 643-648
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
SU(2) Coherent State Path Integral Investigation of the Holstein Dimer
Autorzy:
Hakioğlu, T.
Ivanov, V. A.
Zhuravlev, M. Ye.
Powiązania:
https://bibliotekanauki.pl/articles/2013732.pdf
Data publikacji:
2000-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
03.65.Db
71.36.+c
64.60.Ak
Opis:
The SU(2) coherent state path integral is used to investigate the partition function of the Holstein dimer. This approach naturally takes into account the dynamical symmetry of the model. The ground-state energy and the number of the phonons are calculated as functions of the parameters of the Hamiltonian. The renormalizations of the phonon frequency and electron hopping for bonding and antibonding states are considered. The destruction of quasiclassical mean field solution is discussed.
Źródło:
Acta Physica Polonica A; 2000, 97, 5; 927-930
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Infrared Synchrotron Radiation: from Condensed Matter to Biology Researches
Autorzy:
Marcelli, A.
Iliescu, C.
Powiązania:
https://bibliotekanauki.pl/articles/2028923.pdf
Data publikacji:
2001-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.30.-j
87.64.-t
87.57.-s
41.60.Ap
87.14.Ee
Opis:
Infrared spectroscopy is probably the oldest spectroscopic method applied to investigate materials and chemico-physical phenomena. Nowadays, infrared spectroscopy represents the characterization technique most applied in the industry and in many technological processes. In the last decades a significant progress has been achieved in the use of the intense and brilliant infrared emission from electron storage rings previously used only as VUV and X-ray sources. In the infrared range the low energy of the electron beam does not affect the synchrotron radiation spectral distribution, while high current will make storage rings the most brilliant infrared sources to be used for infrared spectroscopy and micro-spectroscopy. Infrared micro-spectroscopy is a unique technique that combines microscopy and spectroscopy for purposes of micro-analysis. Spatial resolution, within a microscopic field of view, is the goal of the modern infrared micro-spectroscopy applied to condensed matter physics, materials science, biophysics, and now to medicine. Although limited in spatial resolution, infrared is able to resolve chemistry using the contrast of the absorption lines. Fourier transform-infrared micro-spectroscopy using synchrotron radiation is now able to collect data with 2-4 cm^{-1} resolution on the scale of 10-100 seconds up to an area of a few microns opening a new scenario: infrared spectroscopy of entire cells and tissue. Moreover, distributions of functional groups such as proteins, lipids, and nucleic acids can be achieved inside a single living cell with a spatial resolution of a few microns.
Źródło:
Acta Physica Polonica A; 2001, 100, 5; 647-658
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dimensional Reduction and Localization of a Bose-Einstein Condensate in a Quasi-1D Bichromatic Optical Lattice
Autorzy:
Salasnich, L.
Adhikari, S.
Powiązania:
https://bibliotekanauki.pl/articles/1190087.pdf
Data publikacji:
2015-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
03.75.Nt
03.75.Lm
64.60.Cn
67.85.Hj
Opis:
We analyze the localization of a Bose-Einstein condensate in a one-dimensional bichromatic quasi-periodic optical-lattice potential by numerically solving the 1D Gross-Pitaevskii equation (1D GPE). We first derive the 1D Gross-Pitaevskii equation from the dimensional reduction of the 3D quantum field theory of interacting bosons obtaining two coupled differential equations (for axial wave fuction and space-time dependent transverse width) which reduce to the 1D Gross-Pitaevskii equation under strict conditions. Then, by using the 1D Gross-Pitaevskii equation we report the suppression of localization in the interacting Bose-Einstein condensate when the repulsive scattering length between bosonic atoms is sufficiently large.
Źródło:
Acta Physica Polonica A; 2015, 128, 6; 979-982
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thickness Dependence of Effective Critical Exponents in Three-Dimensional Ising Plates
Autorzy:
Marqués, M. I.
Gonzalo, J. A.
Powiązania:
https://bibliotekanauki.pl/articles/2014019.pdf
Data publikacji:
2000-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Hk
64.60.Fr
75.70.-i
02.50.Ng
Opis:
Phase transitions in Ising plates of equal area and different thicknesses have been studied by the Monte Carlo approach. The evolution of the critical temperature and of the effective critical exponents with the thickness of the lattice has been numerically determined. The thickness dependence of the maximum value of the effective critical exponents is well described by an exponential decay towards the respective three-dimensional value.
Źródło:
Acta Physica Polonica A; 2000, 97, 6; 1033-1037
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis, Separation and Electrical Properties of $WO_{3-x}$ Nanopowders via Partial Pressure High Energy Ball-Milling
Autorzy:
Al Mohammad, A.
Powiązania:
https://bibliotekanauki.pl/articles/1807792.pdf
Data publikacji:
2009-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.20.Ev
61.46.Df
64.60.Cn
Opis:
Reduction processes of $WO_{3}$ nanopowder either with carbon or with hydrogen were observed using X-ray powder diffraction and transmission electron microscope. The phase transformations, separation, grain size and electrical conductivity of $WO_{3-x}$ nanopowder during reductions via partial pressure high energy ball-milling have been studied. During the carbon-reduction process the monoclinic $WO_{3}$ structure transforms to nonstoichiometric Magneli phases $W_{40}O_{118}$, $WO_{2.9}$ and finally to $WO_{2}$ and W mixed phases. The Magneli $WO_{3-x}$ phases exhibit specific fringe contrast imaging of well-ordered crystallographic shear planes. In comparison, the monoclinic $WO_{3}$ structure transforms to hydrate $WO_{3}·1/3H_{2}O$, hexagonal $WO_{3}$, non-stoichiometric $WO_{2.7}$ and finally to $WO_{2}$ and W mixed phases during the hydrogen-reduction process. The inclusion of hydrogen atoms between the $WO_{6}$ octahedral structure shifts the reduction steps to lower milling times. It demonstrates that the formation of hydrate $WO_{3}$ phases enhances the amenability of the system to reduction. The activation energy for conduction was deduced from the Arrhenius equation and was found to depend on oxygen partial pressure or presence of the hydrogen atoms. The defect band model was used for interpretation of these behaviors. It supposes that the surface oxygen vacancies introduce donor levels in the gap of semiconductor, so free electrons are produced by reduction.
Źródło:
Acta Physica Polonica A; 2009, 116, 2; 240-244
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical Analyses of Si and GaAs Semiconductors by Fractional-Derivative-Spectrum Methods
Autorzy:
Rzodkiewicz, W.
Kulik, M.
Papis, E.
Szerling, A.
Powiązania:
https://bibliotekanauki.pl/articles/1807507.pdf
Data publikacji:
2009-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.40.Fy
64.60.-f
71.20.-b
Opis:
Optical spectra analysis provides a wealth of information on physical properties of various semiconductor materials. Fractional derivative spectrum technique is especially interesting when the limitations of the standard treatment occur. In this paper we present the fractional derivative spectrum method for analysis of the optical spectra for both Si and GaAs. The significant changes in critical point parameters in each treated Si and GaAs samples in comparison to that before treatment have been observed. Our investigation illustrates that fractional derivative spectrum is a very good technique to extract basic information on relevant physical quantities from the observed optical spectra, and it has the advantages of flexibility, directness, and sensitivity, which give possibility to obtain the Van Hove singularities (critical point parameters) efficiently with one consent.
Źródło:
Acta Physica Polonica A; 2009, 116, S; S-95-S-98
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Earth Materials at High Pressure and Temperature: Recent Contributions from in situ Synchrotron X-Ray Diffraction
Autorzy:
Redfern, S. A. T.
Powiązania:
https://bibliotekanauki.pl/articles/1963306.pdf
Data publikacji:
1997-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.60.-i
07.35.+k
91.35.-x
Opis:
The application of synchrotron X-ray powder diffraction to the study of minerals and understanding of the structure and dynamics of the Earth's deep interior is summarised. The salient features of the diamond anvil cell and large-volume multi-anvil cell high-P/T apparatus as used at synchrotron radiation sources are described, and recent developments and applications of these techniques within high-P/T mineralogy are reviewed.
Źródło:
Acta Physica Polonica A; 1997, 91, 4; 659-668
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Oxidation Behavior of AlTiN/TiN Nanolayer Hard Coating at High Temperatures
Autorzy:
Çalışkan, H.
Karaoğlanlı, A.
Powiązania:
https://bibliotekanauki.pl/articles/1195075.pdf
Data publikacji:
2014-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.60.Dv
64.75.St
52.70.La
68.37.Hk
68.55.Nq
Opis:
Hard machining and high speed cutting are challenging machining processes demanded for high productivity for several decades. Hard coatings are mostly used for protection of the tool materials from severe tribological conditions in which excessive cutting temperatures and forces take place during these processes. Oxidation resistance is an important property of the hard coatings in hard machining operations due to high temperatures up to 1000C at the cutting edge. Improvement of oxidation resistance provides longer tool life at dry cutting conditions. TiAlN-based coatings are known to have high oxidation resistance. In this paper, nanolayer AlTiN/TiN coating was deposited on cemented carbide substrates by industrial magnetron sputtering system. The need to understand the effect of nanolayered structure on the oxidation behavior of protective coatings in machining industry in terms of high temperature oxidation tests is the motivation of this investigation. The deposited coating was annealed at 1000C with different durations. Before and after the oxidation tests, the composition, structure and phases of the coating were determined by scanning electron microscopy in combination with energy-dispersive X-ray spectroscopy and X-ray diffraction, respectively. It was found that nanolayered structure improves oxidation resistance, and thereby, it provides longer tool life.
Źródło:
Acta Physica Polonica A; 2014, 125, 2; 456-458
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical Simulations of Linear S=1 Ferro- and Antiferromagnets
Autorzy:
Kamieniarz, G.
Matysiak, R.
Caramico D'Auria, A.
Esposito, F.
Esposito, U.
Powiązania:
https://bibliotekanauki.pl/articles/1964696.pdf
Data publikacji:
1997-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.60.-i
75.10.Hk
75.40.Mg
Opis:
The finite-temperature static properties of the spin S=1 antiferromagnetic Heisenberg chains are extensively simulated using the quantum transfer matrix method. The zero-field susceptibility and specific heat as well as the field-dependent magnetization data are evaluated to select the microscopic parameters of a number of real quasi-one-dimensional compounds and to verify some theoretical approaches.
Źródło:
Acta Physica Polonica A; 1997, 92, 2; 387-389
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of different SU(3) color representations on the nucleation of quark-gluon plasma droplets from a hadronic gas
Autorzy:
Mezouar, K.
Ait El Djoudi, A.
Powiązania:
https://bibliotekanauki.pl/articles/1070450.pdf
Data publikacji:
2016-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
12.38.Mh
64.60.Qb
02.20.-a
05.70.Ce
Opis:
We study the nucleation of quark-gluon plasma (QGP) droplets from the hadronic gas phase, based on the calculation of the difference in free energy in the QGP and hadronic gas phases. We investigate this difference in free energy by modeling it in different cases, when the surface tension of the QGP bubble is considered or not. We calculate the free energies of both hadronic gas consisting of massive pions and plasma droplet with up, down and strange quarks additionally to gluons, for different SU ≤ft( 3 ıght) color representations of the QGP, namely the color singlet, color octet, and color 27-plet. The behavior of the obtained change in free energy is examined with varying radius of the QGP bubble, and at different temperatures. The effect of the surface contribution on the nucleated bubble is also investigated and compared to the case without this contribution.
Źródło:
Acta Physica Polonica A; 2016, 130, 1; 202-205
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Monte Carlo Study of a Spin-3/2 Blume-Emery-Griffiths Model on a Honeycomb Lattice
Autorzy:
Žukovič, M.
Jaščur, M.
Powiązania:
https://bibliotekanauki.pl/articles/1199541.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.50.+q
64.60.De
75.10.Hk
75.30.Kz
75.50.Lk
Opis:
We study the phase diagram of the spin-3/2 Blume-Emery-Griffiths model on a honeycomb lattice by Monte Carlo simulations in order to verify the presence of some peculiar features predicted by the effective field theory (EFT) with correlations. The locations of the order-disorder phase boundaries are estimated from thermal variations of the magnetic susceptibility curves. It is found that for positive values of the biquadratic interactions the critical boundary shows a discontinuous character as a function of the single-ion anisotropy strength, in line with the EFT expectations. However, for negative values of the biquadratic interactions the step-like variation of the critical frontier predicted by EFT was not reproduced.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 36-37
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Low Field Relaxational Behavior of Taap Single Crystal (20-10$\text{}^{6}$ Hz)
Autorzy:
Fernández del Castillo, J. R.
Iglesias, T.
Przesławski, J.
Gonzalo, J. A.
Powiązania:
https://bibliotekanauki.pl/articles/1968856.pdf
Data publikacji:
1998-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.60.Fr
77.80.-e
Opis:
Relaxational behavior of ferroelectric telluric acid ammonium phosphate crystals were investigated in the range 20 Hz to 1 MHz by means of low field measurements of ε' and tan δ in the vicinity of ferroelectric phase transitions at a number of frequencies. Results are compared with those for triglycine selenate, a much "softer" ferroelectric material. The measuring field and frequency dependence of the effective potential barrier height for domain wall motion are compared in both crystals.
Źródło:
Acta Physica Polonica A; 1998, 93, 3; 499-503
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Complexes of Domain Walls in One-Dimensional Ferromagnets Near and Far from Phase Transition
Autorzy:
Janutka, A.
Powiązania:
https://bibliotekanauki.pl/articles/1399495.pdf
Data publikacji:
2013-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.45.Yv
64.60.Ht
75.70.Kw
75.78.Fg
77.80.Dj
Opis:
Interactions of domain walls are analyzed with relevance to formation of stationary bubbles (bound state of two domain walls) and bound states of many domains in one-dimensional systems. We investigate the domain structures in ferromagnets which are described with the Landau-Lifshitz equation as well as the domains in critical systems described with the Ginzburg-Landau equation. Supplementing previous author studies on the creation of hard bubbles [formed by one Bloch domain wall and one Néel (Ising) domain wall] in the presence of an external (magnetic) field, the soft bubbles consisting of two Bloch domain walls or two Néel (Ising) domain walls are studied in detail. The interactions of two domain walls of the same kind are studied in the framework of a perturbation calculus.
Źródło:
Acta Physica Polonica A; 2013, 124, 1; 23-28
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ellipsometrical and SEM Study of Ferritin Adsorption οn a Gold Surface
Autorzy:
Vladimirova, L.
Tsutsumanova, G.
Gritzkow, Al.
Savov, V.
Powiązania:
https://bibliotekanauki.pl/articles/1795711.pdf
Data publikacji:
2009-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
79.60.Dp
87.64.Ee
87.14.Df
82.45.Jm
Opis:
The adsorption of horse spleen ferritin on gold surface is studied with null ellipsometry and scanning electron microscopy. The high sensitivity and in situ advantage of ellipsometry make it very attractive for studies of ultrathin biomolecular layers. The influence of pH and protein concentration in solution on the adsorption kinetics was interpreted using ex situ scanning electron microscopy shots and computer modeling of the system "prism-gold film-adsorbed layer-solution". It seems that the first fast stage comprises nucleation process occurring at active sites and the following slow multistage process of a protein film growth. The data about adsorption kinetics of protein and the structure of the adsorbate layers obtained in this study enable understanding of such processes in real biological system, e.g. the protein adsorption on blood vessels and tissues in pathological processes.
Źródło:
Acta Physica Polonica A; 2009, 116, 4; 705-707
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Free Volume of Condensed Phases Confined in a Nanopore as Seen by Computer Simulations and Compared to PALS
Autorzy:
Račko, D.
Powiązania:
https://bibliotekanauki.pl/articles/1196175.pdf
Data publikacji:
2014-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
61.20.Ja
76.60.-k
64.70.pm
Opis:
In this contribution the free volume of glycerol phase confined in a nanopore in a wide temperature range is computed. The computed free volume is compared to the previously computed values in the glycerol bulk. The mean cavity volumes are also discussed with the experimental measurements by positronium annihilation lifetime spectroscopy. The computer simulations show that in the case of the confined glycerol phase the mean cavity volumes are larger than in the simulated bulk, and also the temperature dependence has a different qualitative behavior; the computed data are in agreement with experimental measurements performed for glycerol in a pore of comparable size with diameter 6 nm. The simulations also indicate that an aspect of filling a pore is important for experimentalists. In the case of a perfectly sealed pore the cavity volume is observed to rise with decreasing temperature.
Źródło:
Acta Physica Polonica A; 2014, 125, 3; 785-788
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electric and Magnetic Properties of Hydrogels Doped with Cu Ions
Autorzy:
Coşkun, R.
Okutan, M.
Yalçın, O.
Kösemen, A.
Powiązania:
https://bibliotekanauki.pl/articles/1418231.pdf
Data publikacji:
2012-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
52.25.Mq
82.35.-x
42.70.Jk
64.60.-i
76.30.-v
Opis:
The electric and magnetic properties of Cu doped and pure/undoped hydrogels were investigated by impedance spectroscopy and electron spin resonance techniques, respectively. The capacitance and dissipation factor (tan δ) were measured in the frequency range of 100 Hz-10 MHz at room temperature. The Cole-Cole plots for the Cu doped dry and pure dry hydrogels have been used to describe the characteristic change of electrical properties in mentioned temperature interval. The comparison between Cu ions doped and pure/undoped samples is done using the impedance spectroscopy and the electron spin resonance techniques. Electron spin resonance signal for pure, Cu doped wet and Cu doped dry samples are not any power absorption signal, near the symmetric with respect to the resonance field values according to the dry sample and asymmetric for resonance field/base line, respectively.
Źródło:
Acta Physica Polonica A; 2012, 122, 4; 683-687
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electron-Phonon Interaction as a Mechanism of Phase Transition in the $CuInP_{2}S_{6}$ Crystal
Autorzy:
Bercha, D.
Bercha, S.
Glukhov, K.
Sznajder, M.
Powiązania:
https://bibliotekanauki.pl/articles/1376070.pdf
Data publikacji:
2014-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.60.Cn
71.15.Mb
71.70.Ej
Opis:
Studies on the phases of $CuInP_{2}S_{6}$ crystal exhibiting phase transitions of the order-disorder type are performed. A possibility for the cooperative Jahn-Teller effect to occur in this crystal is analyzed. For this purpose, the procedure of constructing the potential energy matrix is generalized for the case of crystal and it is illustrated by the construction of the adiabatic potentials for $Γ_{5}$-$Γ_{5}$ vibronic coupling for the proto- and paraelectric phases of $CuInP_{2}S_{6}$. The structure of the obtained potentials is analyzed together with the discussion on the appearance of spontaneous polarization in this crystal.
Źródło:
Acta Physica Polonica A; 2014, 126, 5; 1143-1145
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin-Peierls Transition in $(N-Me-Tetra-Me-Pz)(TCNQ)_{2}$
Autorzy:
Kajňaková, M.
Botko, M.
Starodub, V.
Čižmár, E.
Feher, A.
Powiązania:
https://bibliotekanauki.pl/articles/1368650.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.60.i
75.10.Jm
75.50.Xx
76.30.v
Opis:
The new organic anion-radical salt $(N-Me-Tetra-Me-Pz)(TCNQ)_{2}$, (Pz = pyrazine) was studied as a low dimensional magnetic system. Heat capacity and EPR studies were performed in the temperature range from 2 to 300 K. The magnetic susceptibility was measured in the temperature range from 2 to 300 K and in magnetic fields of 100 mT and 1 T. The magnetic properties of this new system can be described as a dimerized Heisenberg spin S=1/2 chain possessing a spin-Peierls transition at 42 K.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 254-255
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Molecular Reorientations οf N-n-Hexyltetrachlorophthalimide Studied by $\text{}^1H$ NMR
Autorzy:
Hołderna-Natkaniec, K.
Jurga, K.
Woźniak-Braszak, A.
Walczak, A.
Powiązania:
https://bibliotekanauki.pl/articles/1538203.pdf
Data publikacji:
2010-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
07.05.Tp
31.15.E-
33.20.Ea
64.70.K-
76.60.-k
Opis:
The spin-lattice relaxation times $T_{1}$ and the second moment of $\text{}^{1}H$ NMR line have been employed to study the internal dynamics of protons of N-n-hexyl-tetra-chloro-phthali-mides in the temperature range 80-350 K. The model of internal reorientations has been proposed.
Źródło:
Acta Physica Polonica A; 2010, 117, 4; 537-548
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synchrotron Radiation Photoemission Studies of Fe 3d States in Cd$\text{}_{1-x}$Fe$\text{}_{x}$Se
Autorzy:
Zema, N.
Lama, F.
Piacentini, M.
Felici, A. C.
Dębowska, D.
Kisiel, A.
Mycielski, A.
Olson, C. G.
Powiązania:
https://bibliotekanauki.pl/articles/1931775.pdf
Data publikacji:
1994-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
87.64.Lg
79.60.-i
Opis:
The angle integrated resonant photoemission measurements of Cd$\text{}_{1-x}$Fe$\text{}_{x}$Se were performed for different Fe concentrations (x = 0.00, 0.07, 0.14) in the photon energy range between 30 eV and 70 eV using synchrotron radiation. The ternary compound valence band photoemission spectra show, in comparison to the CdSe results, two additional structures, whose intensity depends on Fe content, which were assigned to Fe 3d states of e symmetry with spin up and down, respectively. The hybridization of the t$\text{}_{2}$ component of the 3d electrons of Fe in the valence band is discussed.
Źródło:
Acta Physica Polonica A; 1994, 86, 5; 861-867
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Acoustic Emission During Firing of the Illite-Based Ceramics with Fly Ash Addition
Autorzy:
Knapek, M.
Húlan, T.
Dobroň, P.
Chmelík, F.
Trník, A.
Štubňa, I.
Powiązania:
https://bibliotekanauki.pl/articles/1402156.pdf
Data publikacji:
2015-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.ph
61.43.Fs
65.60.+a
81.70.Pg
43.40.Le
Opis:
In this work, illite-based ceramic body with power plant fly ash addition (60 wt.% of illite, 30 wt.% of fly ash and 10 wt.% of illite fired at 1100°C) was investigated by the thermal analysis techniques (differential thermal analysis, thermodilatometry and thermogravimetry) and the acoustic emission technique. The green body was heated up to 1100°C at three different rates 2.5, 5, 10 K/min. The most intense acoustic emission was recorded at the highest rate 10 K/min. Mutual correlations between thermal analyses and acoustic emission data were also examined. The first acoustic emission response appears at 430°C, corresponding to a small endotherm on the DTA curve, where the thermal decomposition of mineral portlandite takes place. In the temperature range from 600 to 900°C, high acoustic emission activity correlates with dehydroxylation and expansion of the sample. At temperatures higher than 800°C, the source of acoustic emission signals is the thermal decomposition of calcite. The amorphous phase created from illite at 920°C becomes pyroplastic, therefore it is not documented by the acoustic emission technique.
Źródło:
Acta Physica Polonica A; 2015, 128, 4; 783-786
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Growth Dynamics of Photoinduced Phase Domain in Cyano-Complex Studied by Boundary Sensitive Raman Spectroscopy
Autorzy:
Asahara, A.
Nakajima, M.
Fukaya, R.
Tokoro, H.
Ohkoshi, S.
Suemoto, T.
Powiązania:
https://bibliotekanauki.pl/articles/1490049.pdf
Data publikacji:
2012-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.60.-i
82.50.Hp
78.30.-j
Opis:
Rubidium manganese hexacyanoferrate exhibits charge transfer phase transition from high temperature phase to low temperature phase at 230 K. This phase transition can also be triggered by light irradiation resonantly inducing charge transfer from $Mn^{2+}$ to $Fe^{3+}$. In the present study, boundary sensitive Raman spectroscopy was performed for $Rb_{0.94}Mn[Fe(CN)_6]_{0.98} \cdot 0.2H_2O$ in both cases of photoinduced and thermal phase transition. Since the frequencies of C ≡ N stretching vibration modes are very sensitive to the valence states of the adjacent metal ions, we can quantify the distribution of not only high and low temperature phase but also boundary configurations from the observed spectra. We obtained the time evolution of the fraction ratios of the valence states from the observed peak areas. In the case of photoinduced situation, the boundary increases up to 15% when high temperature phase diminishes to 55% of the initial fraction. This is quite different from the result in thermal phase transition where the boundary is created only 0.8% at the same high temperature phase fraction value. We conclude that many small domains are preferably created in photoinduced phase transition since the ratio of boundary is large, while large domains grow in thermal phase transition.
Źródło:
Acta Physica Polonica A; 2012, 121, 2; 375-384
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ordering in Triangular Lattice Ising Antiferromagnet Due to Dilution and Magnetic Field
Autorzy:
Žukovič, M.
Borovský, M.
Bobák, A.
Powiązania:
https://bibliotekanauki.pl/articles/1506982.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.50.+q
64.60.De
75.10.Hk
75.30.Kz
75.50.Ee
75.50.Lk
Opis:
We study effects of an external magnetic field and random site dilution on the magnetic ordering in the geometrically frustrated triangular lattice Ising antiferromagnet by the use of an effective-field theory with correlations. In particular, we find that already a small amount of the quenched dilution locally relieves the frustration which in the presence of the external field is manifested by multiple splitting of a broad frustration-induced 1/3 magnetization plateau. Depending on the field strength, the dilution can either decrease or increase the magnetization or even change its effect from decreasing to increasing.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 740-741
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Direct Simulations of the Quantum Model for CsNiF$\text{}_{3}$
Autorzy:
Caramico D'Auria, A.
Esposito, F.
Esposito, U.
Kamieniarz, G.
Dekeyser, R.
Powiązania:
https://bibliotekanauki.pl/articles/1930597.pdf
Data publikacji:
1994-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.60.Cn
75.10.Dg
75.10.Jm
75.40.Cx
75.40.Mg
Opis:
We address the problem of reliability of a finite-chain technique for CsNiF$\text{}_{3}$. We investigate the effect of the boundary conditions, completely neglected so far, and apply a new extrapolation procedure appropriate for quantities showing non-monotonic behaviour. From a detailed analysis of the specific heat existing theoretical estimates for the model parameters are discriminated and a strong evidence for the reliability of the direct finite-chain technique predictions is presented.
Źródło:
Acta Physica Polonica A; 1994, 85, 2; 409-412
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
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