Temat: 75.10.Jm - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: J$\text{}_{1}$-J$\text{}_{2}$-J$\text{}_{3}$ Model with Long-Range Lieb-Mattis Interaction
Autorzy:: Krüger, S. E.
Richter, J.
Tematy:: 75.10.Jm; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1955533.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: On the Energy Spectrum and Ground-State Properties οf the Decorated Heisenberg Spin Tube
Autorzy:: Cheranovskii, V.
Ezerskaya, E.
Tematy:: 75.10.Jm; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1534809.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Spin-1/2 XXZ Diamond Chain within the Jordan-Wigner Fermionization Approach
Autorzy:: Verkholyak, T.
Strečka, J.
Jaščur, M.
Richter, J.
Tematy:: 75.10.Jm
75.10.Pq; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1535012.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Frustrated Magnetism in Vanadium Oxides
Autorzy:: Thalmeier, P.
Schmidt, B.
Yushankhai, V.
Takimoto, T.
Tematy:: 75.10.Jm
75.10.Lp; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1810285.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Hidden Domain Walls as Elementary Excitations in the Spin-1 Valence-Bond-Solid Model
Autorzy:: Fáth, G.
Sólyom, J.
Tematy:: 75.10.Jm; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1930581.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Real-Space Pair Model Predictions for the NMR Behaviour in High-T_{c} Cuprates
Autorzy:: Mukhin, S. I.
Tematy:: 75.10.Jm; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1861012.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Lieb-Mattis Model for Two Interpenetrating Antiferromagnets
Autorzy:: Schmalfuss, D.
Krüger, S. E.
Richter, J.
Tematy:: 75.10.Jm; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2012975.pdf Link otwiera się w nowym oknie
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$\text{}_{2}$.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Critical and Massive Phases in Spin Chains and Spin Ladders
Autorzy:: Sólyom, J.
Tematy:: 75.10.Jm; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2011223.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Ultra-Fast Spin Dynamics in Diluted Magnetic Semiconductors
Autorzy:: Wilamowski, Z.
Buczko, R.
Karczewski, G.
Jantsch, W.
Tematy:: 75.10.Jm
75.50.-y; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1952363.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Collective Excitations in Heisenberg Ultrathin Films with Inhomogeneous Spatial Distribution of Magnetisation
Autorzy:: Łosiński, R.
Onyszkiewicz, Z.
Tematy:: 75.70.-i
75.10.Jm; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2014320.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

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