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Wyszukujesz frazę "75.10.Jm" wg kryterium: Temat


Tytuł:
J$\text{}_{1}$-J$\text{}_{2}$-J$\text{}_{3}$ Model with Long-Range Lieb-Mattis Interaction
Autorzy:
Krüger, S. E.
Richter, J.
Powiązania:
https://bibliotekanauki.pl/articles/1955533.pdf
Data publikacji:
1997-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Jm
Opis:
Stimulated by the two-dimensional frustrated Heisenberg antiferromagnet with first-, second-, and third-neighbor couplings (J$\text{}_{1}$-J$\text{}_{2}$-J$\text{}_{3}$ model) we consider a corresponding three-parameter model with a long-range antiferromagnetic Lieb-Mattis interaction. This model can be solved exactly and leads to a better understanding of the role of frustration in the J$\text{}_{1}$-J$\text{}_{2}$-J$\text{}_{3}$ model. We calculate the correlations in the groundstate and consider their finite size behavior. Furthermore we present the full thermodynamic phase diagram. We find the possibility of a disordered phase at T=0.
Źródło:
Acta Physica Polonica A; 1997, 91, 2; 377-380
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the Energy Spectrum and Ground-State Properties οf the Decorated Heisenberg Spin Tube
Autorzy:
Cheranovskii, V.
Ezerskaya, E.
Powiązania:
https://bibliotekanauki.pl/articles/1534809.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Jm
Opis:
The ground-state properties of decorated Heisenberg spin tubes with nearest- and next-nearest-neighbor antiferromagnetic exchange interactions has been studied using perturbation theory and exact diagonalization technique. The possibility of quantum phase transitions mediated by next-nearest neighbor interactions for these tubes is shown.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 946-947
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hidden Domain Walls as Elementary Excitations in the Spin-1 Valence-Bond-Solid Model
Autorzy:
Fáth, G.
Sólyom, J.
Powiązania:
https://bibliotekanauki.pl/articles/1930581.pdf
Data publikacji:
1994-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Jm
Opis:
Low-energy excitations are studied in the 1D S = 1 antiferromagnetic valence-bond-solid model. The lowest states are found to form a discrete triplet branch, separated from a higher-lying scattering continuum. The elementary excitations are argued to be "hidden" domain walls.
Źródło:
Acta Physica Polonica A; 1994, 85, 2; 371-375
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Real-Space Pair Model Predictions for the NMR Behaviour in High-T_{c} Cuprates
Autorzy:
Mukhin, S. I.
Powiązania:
https://bibliotekanauki.pl/articles/1861012.pdf
Data publikacji:
1994-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Jm
Opis:
A model for real-space singlet pairs, hopping on the quasi 2D antiferromagnetic background of localized spins is further analysed. It is shown that lattice vibrations (if any), which break the symmetry of the in-plane oxygen position with respect to the nearest neighboring copper sites, may strongly influence both the magnitude and the temperature dependence of the$\text{} ^{17}$O NMR relaxation rate. For the Y site a situation is analogous, although the different modes may contribute to the effect. A relation of the results obtained to the Millis-Monien-Pines analysis is discussed. The validity of the mean-field random phase approximation for the description of the 2D antiferromagnet used previously is analysed. It is shown that the 2D fluctuations of the phase of the (bond) mean field parameter lead to the power-law decay with the distance of the corresponding correlation function (which remains finite in the mean field approximation). The spectrum of the phase fluctuations is found to be propagative in the one-loop approximation. An interaction of the real-space singlet pairs with the long-wavelength phase fluctuations is discussed.
Źródło:
Acta Physica Polonica A; 1994, 85, 1; 133-143
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Lieb-Mattis Model for Two Interpenetrating Antiferromagnets
Autorzy:
Schmalfuss, D.
Krüger, S. E.
Richter, J.
Powiązania:
https://bibliotekanauki.pl/articles/2012975.pdf
Data publikacji:
2000-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Jm
Opis:
We investigate a frustrated Lieb-Mattis-like spin-1/2 model that is a reference model for the corresponding square-lattice Heisenberg model describing the unusual magnetic properties of Ba$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{4}$Cl$\text{}_{2}$. Due to frustration we obtain a rich magnetic phase diagram. We find two critical temperatures in accordance with recent experiments on Ba$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{4}$Cl$\text{}_{2}$.
Źródło:
Acta Physica Polonica A; 2000, 97, 3; 377-380
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Critical and Massive Phases in Spin Chains and Spin Ladders
Autorzy:
Sólyom, J.
Powiązania:
https://bibliotekanauki.pl/articles/2011223.pdf
Data publikacji:
2000-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Jm
Opis:
Spin chains and spin ladders can have a variety of gapless (critical) or gapped (massive) phases depending on the length of the spin and the type of coupling. A brief review of the results on some simple models is given with emphasis on the generation of the Haldane gap in anisotropic spin ladders.
Źródło:
Acta Physica Polonica A; 2000, 97, 1; 81-90
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin-1/2 XXZ Diamond Chain within the Jordan-Wigner Fermionization Approach
Autorzy:
Verkholyak, T.
Strečka, J.
Jaščur, M.
Richter, J.
Powiązania:
https://bibliotekanauki.pl/articles/1535012.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Jm
75.10.Pq
Opis:
The spin-1/2 XXZ diamond chain is considered within the Jordan-Wigner fermionization. The fermionized Hamiltonian contains the interacting terms which are treated within the Hartree-Fock approximation. We obtain the ground-state magnetization curve of the model for some particular cases and compare the results with the exact diagonalization data for finite chains of 30 spins and known exact results. We also analyze the validity of the suggested approximation.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 978-979
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Frustrated Magnetism in Vanadium Oxides
Autorzy:
Thalmeier, P.
Schmidt, B.
Yushankhai, V.
Takimoto, T.
Powiązania:
https://bibliotekanauki.pl/articles/1810285.pdf
Data publikacji:
2009-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Jm
75.10.Lp
Opis:
The effect of frustration in various localized and itinerant vanadium oxide compounds is discussed within next nearest neighbors Heisenberg and spin fluctuation models, respectively. In the localized moment case the S=1/2 $J_1-J_2$-model on a square lattice exhibits a rich phase diagram with magnetic as well as exotic hidden order phases due to the interplay of frustration and quantum fluctuations. Their signatures in the high field magnetization and in magnetocaloric quantities are surveyed. The possible quantum phase transitions are discussed and applied to layered vanadium oxides of the type $AA'VO(PO_4)_2$ where A, A' = Pb, Zn, Sr, Ba, Cd. In itinerant electron systems magnetic frustration may emerge as a result of electron correlations on a geometrically frustrated lattice. This mechanism causes enhanced spin fluctuations in a large region of momentum space and therefore can lead to a heavy fermion state at low temperatures as in the 3d spinel compound $LiV_2O_4$. The evidence from neutron scattering and NMR experiments is discussed within self-consistent renormalization theory based on local density approximation band structure calculations.
Źródło:
Acta Physica Polonica A; 2009, 115, 1; 53-58
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ultra-Fast Spin Dynamics in Diluted Magnetic Semiconductors
Autorzy:
Wilamowski, Z.
Buczko, R.
Karczewski, G.
Jantsch, W.
Powiązania:
https://bibliotekanauki.pl/articles/1952363.pdf
Data publikacji:
1996-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Jm
75.50.-y
Opis:
In nano-size antiferromagnetic systems a spatially inhomogeneous field leads to the formation of a staggered magnetization. Thereby the total magnetic moment does not change but the formation of a net magnetic moment at the border of the cluster leads to an energy gain. This type of magnetism is characterised by an ultra-fast dynamics. We suggest it is also responsible for the formation of the exciton magnetic polaron.
Źródło:
Acta Physica Polonica A; 1996, 90, 5; 969-972
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Collective Excitations in Heisenberg Ultrathin Films with Inhomogeneous Spatial Distribution of Magnetisation
Autorzy:
Łosiński, R.
Onyszkiewicz, Z.
Powiązania:
https://bibliotekanauki.pl/articles/2014320.pdf
Data publikacji:
2000-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.70.-i
75.10.Jm
Opis:
The influence of non-magnetic substrate on the collective excitation of the Heisenberg (s=1/2) ferromagnetic ultrathin films with homogeneous and inhomogeneous spatial distribution of magnetization is investigated. It has been proved that the collective excitation spectrum of ultrathin film may, to a significant degree, depend on the value of the coefficient characterizing the film coupling with its substrate.
Źródło:
Acta Physica Polonica A; 2000, 98, 4; 419-428
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Energy Spectrum and Thermodynamics of Spin-1/2 XX Chain with Ising Impurities
Autorzy:
Ezerskaya, E.
Powiązania:
https://bibliotekanauki.pl/articles/1032134.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Jm
75.40.Cx
Opis:
The energy spectrum and peculiarities of field and temperature dependences of the basic thermodynamic characteristics of the finite spin-1/2 XX chain closed by one zz (Ising) bond and open ends XX-chain with two zz-impurities at the both ends have been investigated.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 928-930
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamic Properties of Spin-1/2 XX Chain with Three-Site Interactions of (XZY - YZX)-Type
Autorzy:
Topilko, M.
Derzhko, O.
Krokhmalskii, T.
Powiązania:
https://bibliotekanauki.pl/articles/1505128.pdf
Data publikacji:
2011-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Jm
75.40.Gb
Opis:
We consider the spin-1/2 isotropic XY chain in a transverse field with three-site interactions of (XZY - YZX)-type, which can be transformed into a system of noninteracting spinless fermions. We study dynamic properties of the spin model. In particular, we calculate the dynamic structure factors which are governed by a two-fermion excitation continuum. We demonstrate how the three-site interactions manifest themselves in the dynamic properties of the quantum spin chain.
Źródło:
Acta Physica Polonica A; 2011, 119, 6; 868-870
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Localized Spin Relaxation Due To Coupling To Effective Mass States
Autorzy:
Wilamowski, Z.
Dmochowski, J. E.
Jantsch, W.
Powiązania:
https://bibliotekanauki.pl/articles/1968446.pdf
Data publikacji:
1997-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Jm
75.50.-y
Opis:
The EPR of residual Mn in CdF$\text{}_{2}$ doped with Y, In and Ga is investigated. Although these donors are barely seen in EPR, they manifest themselves by a new effect: a drastic resonant reduction in the longitudinal relaxation rate of Mn which occurs only if the Zeeman splitting of the two subsystems coincide. In this situation, the saturation of those of the six Mn hyperfine lines is weakened which coincide with the shallow donor resonance.
Źródło:
Acta Physica Polonica A; 1997, 92, 5; 1055-1058
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Quantum Phenomena in Small Antiferromagnets
Autorzy:
Wilamowski, Z.
Buczko, R.
Jantsch, W.
Powiązania:
https://bibliotekanauki.pl/articles/1964697.pdf
Data publikacji:
1997-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Jm
75.50.-y
Opis:
We show that the most characteristic properties of mesoscopic antiferromagnets can be explained in terms of the response on a spatially inhomogeneous perturbation. This concept allows to explain the dynamic properties (quantum resonance, coherence and tunnelling rates) as well as static perturbations which, for increasing size of an antiferromagnet, leads to a transition from the quantum mechanical oscillating system to a classical antiferromagnet with well defined Néel vectors.
Źródło:
Acta Physica Polonica A; 1997, 92, 2; 379-382
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Antiferromagnetic Order in the Hubbard Model: Spin-Charge Rotating Reference Frame Approach
Autorzy:
Zaleski, T.
Kopeć, T.
Powiązania:
https://bibliotekanauki.pl/articles/1812334.pdf
Data publikacji:
2008-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.Fd
75.10.Jm
Opis:
We study the antiferromagnetic phase of three-dimensional Hubbard model with nearest neighbors hopping on a bipartite cubic lattice. We use the quantum SU(2)×U(1) rotor approach that yields a fully self-consistent treatment of the antiferromagnetic state that respects the symmetry properties of the model and satisfies the Mermin-Wagner theorem. As our theory describes the evolution from a Slater (U ≪ t) to a Mott-Heisenberg (U ≫ t) antiferromagnet, we present the phase diagram of the antiferromagnetic Hubbard model as a function of the crossover parameter U/t.
Źródło:
Acta Physica Polonica A; 2008, 114, 1; 247-251
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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