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    Wyświetlanie 1-23 z 23
    Tytuł:
    Improved Nucleation and Transition by Plasma Treatments for Fast Response Optically-Compensated-Bend Displays
    Autorzy:
    Wu, G.
    Huang, C.
    Chien, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/1400462.pdf
    Data publikacji:
    2013-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    52.77.-j
    81.65.-b
    42.79.Kr
    64.60.Q-
    Opis:
    The optically-compensated-bend mode pi-cell displays exhibit fast-response time and wide-viewing angle characteristics. However, it requires a transition of the liquid crystal molecule from an initial splay state to the bend state configuration before providing the quick operation. A high voltage and a long warm-up time are needed to transform to the bend state. In this paper, the polyimide alignment films have been modified to reduce the splay-to-bend transition time by plasma beam treatments. The proposed method was demonstrated to be highly effective in improving the overall transition time. The number of splay-to-bend nucleation sites in the assembled liquid crystal cells could be increased dramatically by up to 20 times at the initial stage, and the improvement in the cell warm-up time was achieved at 45-71% reduction at 5.5 V. The plasma processing parameters were optimized at the plasma power of 700 W, the plasma distance of 25 mm, and the plasma scan speed of 600 mm/s. In addition, we maintained the excellent optical properties and response time characteristics for the optically-compensated-bend mode liquid crystal displays.
    Źródło:
    Acta Physica Polonica A; 2013, 123, 5; 892-895
    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:
    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:
    Orientational Ordering for System of Ellipsoidal Molecules Dispersed in Cubic Lattice
    Autorzy:
    Mejdani, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/1952744.pdf
    Data publikacji:
    1996-12
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    05.50.+q
    64.60.Cn
    64.60.My
    64.70.Md
    Opis:
    We represent here some results for a model of migrating and nonmigrating ellipsoidal molecules dispersed in a cubic lattice, describing: the orientational ordering in nematics, the possibility of a biaxial ordered liquid state, the orientational ordering in solid hydrogen (orto-H$\text{}_{2}$ or para-D$\text{}_{2}$) or the orientational glassy structure (the "higher rank"glass state). Through this kind of molecular ensemble (in the case of the system of ellipsoidal and spherical molecules) it is also possible to study the orientational and positional orderings in binary mixtures and to obtain the so-called plastic state.
    Źródło:
    Acta Physica Polonica A; 1996, 90, 6; 1127-1141
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Critical Behaviour of Some 2D Lattice Models
    Autorzy:
    Kamieniarz, G.
    Blöte, H. W.J.
    Dekeyser, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/1930586.pdf
    Data publikacji:
    1994-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    05.50.+q
    64.60.-i
    64.60.Cn
    64.60.Ak
    64.60.Fr
    75.40.Mg
    Opis:
    The density series of the non-interacting hard-square lattice gas model are reanalyzed by the ratio, Dlog Padé and differential approximant methods. The problem of poor consistency between series and other results is resolved. Transfer matrix calculations are performed, implementing both finite-size scaling and conformal invariance. Very accurate estimates of the critical exponents y$\text{}_{t}$, and y$\text{}_{h}$ are obtained in agreement with Ising universality. Furthermore, an improvement of the value of the critical density ρ$\text{}_{c}$ is found. In addition, the universal critical-point ratios of the square of the second and the fourth moment of the magnetization for ferromagnetic Ising models on the square and on the triangular lattice with periodic boundary conditions are reported.
    Źródło:
    Acta Physica Polonica A; 1994, 85, 2; 389-393
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Simulations of the 3D Ising Model at Criticality
    Autorzy:
    Blöte, H. W. J.
    Kamieniarz, G.
    Powiązania:
    https://bibliotekanauki.pl/articles/1930588.pdf
    Data publikacji:
    1994-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    05.50.+q
    64.60.-i
    64.60.Fr
    75.40.Mg
    64.60.Ak
    Opis:
    We present some new finite-size results for the Binder cumulant that we obtained by means of a transfer-matrix perturbation expansion and by the cluster Monte Carlo methods - the Swendsen-Wang and Wolff algorithms and the largest-cluster method. A finite-size scaling analysis taking into account a correction to scaling locates the critical coupling at Kc = 0.221649(4).
    Źródło:
    Acta Physica Polonica A; 1994, 85, 2; 395-398
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    On Gibbs Measures of the Potts Model with Three Competing Interactions on Cayley Tree of Order 3
    Autorzy:
    Akin, H.
    Saygılı, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/1186977.pdf
    Data publikacji:
    2016-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    05.50.+q
    64.60.-i
    75.10.Hk
    64.60.De
    Opis:
    In this paper, we consider the Potts model with competing interactions on the Cayley tree of order three. We give the Potts model on the Cayley tree and its recursion relation. We construct the Gibbs states corresponding to the model by using Markov random field method. We calculate the critical curve, such that there is a phase transition for the model. We show that there are phase transition of the model for some given parameters. We extend the results obtained by Akin and Temir (Condensed Matt. Phys. 14, 23003 (2011)).
    Źródło:
    Acta Physica Polonica A; 2016, 129, 4; 845-848
    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:
    Description of Extreme Gibbs Measures for the Ising Model with Three Interactions
    Autorzy:
    Akin, H.
    Ganikhodjaev, N.
    Temir, S.
    Uguz, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/1400048.pdf
    Data publikacji:
    2013-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    05.50.+q
    64.60.-i
    64.60.De
    75.10.Hk
    Opis:
    In this paper, we consider an Ising model with three competing interactions (nearest neighbor, next-nearest neighbor, and ternary prolonged neighbor) on the Cayley tree of order two, investigated by Ganikhodjaev et al. We study translation-invariant Gibbs measures of the Ising model with these competing interactions. Also, we investigate the set of the extreme Gibbs measures called Markov random fields with memory 2 of the model.
    Źródło:
    Acta Physica Polonica A; 2013, 123, 2; 484-487
    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 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:
    Simulated Annealing with Tsallis Weights for ±J Spin Glass
    Autorzy:
    Kłos, J.
    Kobe, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/2013971.pdf
    Data publikacji:
    2000-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    05.50.+q
    64.60.Cn
    75.10.Hk
    Opis:
    Recently, on the basis of the Tsallis distribution of states the generalized Monte Carlo acceptance probabilities have been proposed and applied to various optimization problems. In the paper we used the generalized simulated annealing algorithms for the ±J spin glass model. Efficiency of the new annealing procedures was compared with that of the conventional methods. This was done with respect to the number of annealing steps and to the lowest energy found. The algorithms were applied to a system of 70×70 spins on a square lattice with periodical boundary conditions whose ground state configurations are known exactly. This enables us to evaluate the efficiency in a quantitative way.
    Źródło:
    Acta Physica Polonica A; 2000, 97, 5; 943-946
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Kondo Lattice Models and Magnetism for Cerium and Uranium Systems
    Autorzy:
    Coqblin, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/1534596.pdf
    Data publikacji:
    2010-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.30.Mb
    75.20.Hr
    05.50.+q
    64.60.Cn
    Opis:
    The interplay between the Kondo effect and magnetism is important in anomalous rare-earth and actinide systems and a brief review of the different Kondo lattice models is presented here. The first studied case is the classical Kondo lattice model with S = 1/2 spins for the 4f localized electrons, which describes the strong competition between the Kondo effect and magnetic ordering leading to small ordering temperatures less than roughly 10 K. The second reviewed case describes the underscreened Kondo lattice model with S = 1 spins for the 5f localized electrons, which can account for the coexistence of both the Kondo effect and the ferromagnetic order and, therefore, the large Curie temperatures observed in actinide compounds like UTe and $NpNiSi_2$; the question of the delocalization of the 5f electrons is also discussed here. The last case describes the competition between the "spin glass" behaviour, the Kondo effect and the magnetic ordering in disordered cerium alloys like $CeNi_{x}Cu_{1 - x}$ or $CeRh_{x}Pd_{1 - x}$ and several models used for the spin glass state are reviewed, as well as the occurrence of magnetic glass clusters.
    Źródło:
    Acta Physica Polonica A; 2010, 118, 5; 913-918
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Finite-Size Scaling Study of Five-Dimensional Ising Model
    Autorzy:
    Merdan, Z.
    Aras, N.
    Kürkçü, C.
    Powiązania:
    https://bibliotekanauki.pl/articles/1398913.pdf
    Data publikacji:
    2016-06
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    05.50.+q
    64.60.Cn
    75.40.Cx
    75.40.Mg
    Opis:
    The five-dimensional ferromagnetic Ising model is simulated on the Creutz cellular automaton algorithm using finite-size lattices with linear dimension 4 ≤ L ≤ 8. The critical temperature value of infinite lattice is found to be $T^{χ}$ (∞=8.7811 (1) using 4 ≤ L ≤ 8 which is also in very good agreement with the precise result. The value of the field critical exponent (δ =3.0067(2)) is good agreement with δ =3 which is obtained from scaling law of Widom. The exponents in the finite-size scaling relations for the magnetic susceptibility and the order parameter at the infinite-lattice critical temperature are computed to be 2.5080 (1), 2.5005 (3) and 1.2501 (1) using 4 ≤ L ≤ 8, respectively, which are in very good agreement with the theoretical predictions of 5/2 and 5/4. The finite-size scaling plots of magnetic susceptibility and the order parameter verify the finite-size scaling relations about the infinite-lattice temperature.
    Źródło:
    Acta Physica Polonica A; 2016, 129, 6; 1100-1104
    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:
    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:
    Ground-State Properties of the Spin-1/2 Heisenberg-Ising Bond Alternating Chain with Dzyaloshinskii-Moriya Interaction
    Autorzy:
    Strečka, J.
    Gálisová, L.
    Derzhko, O.
    Powiązania:
    https://bibliotekanauki.pl/articles/1506983.pdf
    Data publikacji:
    2010-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    05.50.+q
    05.70.Jk
    64.60.De
    75.10.Pq
    Opis:
    Ground-state energy is exactly calculated for the spin-1/2 Heisenberg-Ising bond alternating chain with the Dzyaloshinskii-Moriya interaction. Under certain condition, which relates a strength of the Ising, Heisenberg and Dzyaloshinskii-Moriya interactions, the ground-state energy exhibits an interesting nonanalytic behavior accompanied with a gapless excitation spectrum.
    Źródło:
    Acta Physica Polonica A; 2010, 118, 5; 742-744
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Magnetism and Kondo Effect in Cerium and Uranium Compounds
    Autorzy:
    Coqblin, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/1813756.pdf
    Data publikacji:
    2008-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.20.Hr
    75.30.Mb
    05.50.+q
    64.60.Cn
    Opis:
    A brief review of the Kondo lattice problem is presented, with a special emphasis on the underscreened Kondo effect in ferromagnetic-Kondo uranium compounds and on the spin glass-Kondo competition in disordered heavy fermion cerium alloys.
    Źródło:
    Acta Physica Polonica A; 2008, 113, 1; 391-394
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effective Field Methods for Magnetic Systems
    Autorzy:
    Kamieniarz, G.
    Dekeyser, R.
    Musiał, G.
    Powiązania:
    https://bibliotekanauki.pl/articles/1930600.pdf
    Data publikacji:
    1994-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.60.Cn
    64.60.Fr
    05.50.+q
    75.10.Dg
    75.10.Hk
    75.10.Jm
    75.40.Cx
    75.40.Mg
    Opis:
    The self-consistency conditions inherent in the mean-field approximation are extended to take into account some pair correlations. Ii is shown that this extension is systematically improvable and applicable to the spin systems with short-range interactions in the entire temperature region. With two correlations included and the renormalization-group ideas implemented, the critical properties of the Ising model are satisfactorily revealed. Moreover, the improved estimates of the thermodynamical quantities for the quantum linear XY model from the finite-size calculations are found down to very low temperatures.
    Źródło:
    Acta Physica Polonica A; 1994, 85, 2; 413-417
    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:
    Mechanisms of Carrier Transport in $Cu_x(SiO_2)_{1-x}$ Nanocomposites Manufactured by Ion-Beam Sputtering with Ar Ions
    Autorzy:
    Fedotov, A.
    Mazanik, A.
    Svito, I.
    Saad, A.
    Fedotova, V.
    Czarnacka, K.
    Koltunowicz, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/1402220.pdf
    Data publikacji:
    2015-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    84.37.+q
    72.80.Ga
    73.22.-f
    61.46.Df
    64.60.ah
    Opis:
    The present paper investigates the temperature/frequency dependences of admittance Z in the granular $Cu_x(SiO_2)_{1-x}$ nanocomposite films around the percolation threshold $x_{C}$ in the temperature range of 4-300 K and frequencies of 20-10⁶ Hz. The behavior of low-frequency ReZ(T) dependences displayed the predominance of electrons hopping between the closest Cu-based nanoparticles for the samples below the percolation threshold $x_{C}$ ≈ 0.59 and nearly metallic behaviour beyond the $x_{C}$. The high-frequency curves ReZ(f) at temperatures T > 10 K for the samples with x < $x_{C}$ exhibited behavior close to ReZ(f) ≈ $f^{-s}$ with s ≈ 1.0 which is very similar to the known Mott law for electron hopping mechanism. For the samples beyond the percolation threshold (x > $x_{C}$), the frequency dependences of ReZ(f) displayed inductive-like (not capacitive) behaviour with positive values of the phase shift angles.
    Źródło:
    Acta Physica Polonica A; 2015, 128, 5; 883-886
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Percolation Phenomena in $Cu_{x}(SiO_{y})_{100-x}$ Nanocomposite Films Produced by Ion Beam-Sputtering
    Autorzy:
    Koltunowicz, T.
    Zukowski, P.
    Czarnacka, K.
    Svito, I.
    Fedotov, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1402230.pdf
    Data publikacji:
    2015-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    84.37.+q
    72.80.Ga
    73.22.-f
    61.46.Df
    64.60.ah
    Opis:
    In this paper the results of examinations of nanocomposites $Cu_{x}(SiO_{y})_{100-x}$ produced by ion beam sputtering using argon ions were presented. The examinations were performed by the use of ac devices for measuring frequency in the range 50 Hz-1 MHz and temperatures from 81 K to 273 K. The measurements were performed for the samples directly after production. Based on temperature dependences of conductivity σ , which were determined at the frequency 100 Hz, the Arrhenius graphs were prepared. From these graphs conductivity activation energies ΔE were calculated. Dependences of conductivity and activation energy of electrons on the metallic phase content x at the frequency 100 Hz were determined. Analysis of the obtained dependences shows that conductivity is a parabolic function of the metallic phase content x in nanocomposites. Changes of activation energies of nanocomposites, in which metallic phase contents are in the ranges x < 12 at.% and x > 68 at.%, demonstrate negative values - metallic type of conductivity. In the range 12 at.% < x < 68 at.% activation energies have positive values - the dielectric type of conductivity. It was established that for the metallic phase content of about 68 at.% the real percolation threshold occurs, and the conduction changes from dielectric to metallic type.
    Źródło:
    Acta Physica Polonica A; 2015, 128, 5; 908-911
    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
      Wyświetlanie 1-23 z 23

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