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Tytuł:
A Coupled Spin-Electron Diamond Chain with Different Landé g-Factors of Localized Ising Spins and Mobile Electrons
Autorzy:
Torrico, J.
Pereira, M.
Strečka, J.
Lyra, M.
Powiązania:
https://bibliotekanauki.pl/articles/1032419.pdf
Data publikacji:
2017-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.50.+q
75.10.Pq
75.30.Kz
75.40.Cx
Opis:
A coupled spin-electron diamond chain with localized Ising spins placed on its nodal sites and mobile electrons delocalized over interstitial sites is explored in a magnetic field taking into account the difference between the Landé g-factors of the localized spins and mobile electrons. The ground-state phase diagram is constituted by two classical ferrimagnetic phases, the quantum unsaturated paramagnetic phase and the saturated paramagnetic phase. Both classical ferrimagnetic phases as well as the unsaturated paramagnetic phase are reflected in a low-temperature magnetization curve as intermediate magnetization plateaus. The unsaturated paramagnetic phase is quantum in its character as evidenced by the fermionic concurrence calculated for a pair of the mobile electrons hopping in between the interstitial sites. It is shown that the magnetic field can under certain conditions induce a quantum entanglement above the disentangled ground state.
Źródło:
Acta Physica Polonica A; 2017, 132, 1; 140-142
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Anomalous Magnetocaloric Properties of the Spin-1/2 Ising Model on a Decorated Square Lattice in a Vicinity of Second-Order Phase Transition
Autorzy:
Karľová, K.
Strečka, J.
Powiązania:
https://bibliotekanauki.pl/articles/1032487.pdf
Data publikacji:
2017-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Hk
75.30.Sg
75.40.-s
75.50.Cc
Opis:
Magnetocaloric properties of the spin-1/2 Ising model on a decorated square lattice in a transverse magnetic field are investigated by the use of a generalized decoration-iteration transformation, which establishes a rigorous mapping correspondence with the zero-field spin-1/2 Ising model on a square lattice. The temperature dependence of the entropy, the isothermal entropy change and the adiabatic temperature change display anomalous singular behavior in a vicinity of a second-order phase transition. The large inverse magnetocaloric effect can be found in the isothermal entropy change within the temperature interval, which is delimited by the critical temperatures at zero and non-zero transverse fields.
Źródło:
Acta Physica Polonica A; 2017, 132, 1; 170-172
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Breakdown of a Magnetization Plateau in Ferrimagnetic Mixed Spin-(1/2,S) Heisenberg Chains due to a Quantum Phase Transition towards the Luttinger Spin Liquid
Autorzy:
Strečka, J.
Powiązania:
https://bibliotekanauki.pl/articles/1032725.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Pq
75.10.Kt
75.30.Kz
75.40.Cx
75.60.Ej
Opis:
Magnetization curves of the ferrimagnetic mixed spin-(1/2,S) Heisenberg chains are calculated with the help of density-matrix renormalization group method for several quantum spin numbers S=1, 3/2, 2 and 5/2. It is shown that the ferrimagnetic mixed spin-(1/2,S) Heisenberg chains exhibit irrespective of the spin value S exactly one intermediate magnetization plateau, which can be identified with the gapped Lieb-Mattis ferrimagnetic ground state. The magnetization plateau due to the Lieb-Mattis ferrimagnetism breaks down at a quantum phase transition towards the Luttinger spin liquid, which is characterized by a continuous change of the magnetization with the magnetic field until another quantum critical point is reached at the saturation field.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 624-626
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of the Canting of Local Anisotropy Axes on Ground-State Properties of a Ferrimagnetic Chain with Regularly Alternating Ising and Heisenberg Spins
Autorzy:
Torrico, J.
Lyra, M.
Rojas, O.
de Souza, S.
Strečka, J.
Powiązania:
https://bibliotekanauki.pl/articles/1032717.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Pq
75.10.Kt
75.30.Kz
75.40.Cx
75.60.Ej
Opis:
The effect of the canting of local anisotropy axes on the ground-state phase diagram and magnetization of a ferrimagnetic chain with regularly alternating Ising and Heisenberg spins is exactly examined in an arbitrarily oriented magnetic field. It is shown that individual contributions of the Ising and Heisenberg spins to the total magnetization basically depend on the spatial orientation of the magnetic field and the canting angle between two different local anisotropy axes of the Ising spins.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 621-623
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Inverse magnetocaloric effect in spin-1/2 Fishers super-exchange antiferromagnet
Autorzy:
Gálisová, L.
Strečka, J.
Powiązania:
https://bibliotekanauki.pl/articles/1052954.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.50.+q
75.30.Et
75.30.Sg
75.30.Kz
Opis:
The isothermal entropy change and the adiabatic temperature change are rigorously calculated for the exactly solved spin-1/2 Fisher's super-exchange antiferromagnet in order to examine magnetocaloric properties of the model in a vicinity of the second-order phase transition. It is shown that the large inverse magnetocaloric effect occurs around the temperature interval T_c(h≠0) < T < T_c(h=0) for any magnetic-field change Δh:0 → h. The most pronounced inverse magnetocaloric effect can be found for the magnetic-field change, which coincides with the critical field of a zero-temperature phase transition from the antiferromagnetically ordered ground state to the paramagnetic one.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 627-629
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Isothermal Entropy Change and Adiabatic Change of Temperature of the Antiferromagnetic Spin-1/2 Ising Octahedron and Dodecahedron
Autorzy:
Karľová, K.
Strečka, J.
Madaras, T.
Powiązania:
https://bibliotekanauki.pl/articles/1032208.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.10.Hk
75.50.Ee
75.50.Xx
Opis:
The spin-1/2 Ising octahedron and dodecahedron with a unique antiferromagnetic interaction display an outstanding magnetization jump at zero magnetic field, which consequently leads to a giant magnetocaloric effect during the adiabatic demagnetization. In the present work we report temperature dependences of two basic magnetocaloric response functions: the isothermal entropy change and the adiabatic change of temperature. It is shown that the Ising octahedron and dodecahedron generally exhibit a large negative isothermal entropy change upon increase of the magnetic field, which serves in evidence of their cooling performance.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 630-632
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Rise and Fall of Reentrant Phase Transitions in a Coupled Spin-Electron Model on a Doubly Decorated Honeycomb Lattice
Autorzy:
Čenčariková, H.
Strečka, J.
Powiązania:
https://bibliotekanauki.pl/articles/1032648.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.50.+q
05.70.Fh
71.27.+a
75.30.Kz
Opis:
Phase diagrams and spontaneous magnetization are rigorously calculated for a coupled spin-electron model on a doubly decorated honeycomb lattice, which accounts for a quantum-mechanical hopping of the mobile electrons on decorating sites, the nearest-neighbor Ising coupling between mobile electrons and localized spins, as well as the further-neighbor Ising coupling between the localized spins placed on nodal sites. The spontaneously ordered ferromagnetic phase, spontaneously ordered antiferromagnetic phase and disordered paramagnetic phase emerge in a phase diagram depending on an electron filling of the decorating sites, a relative size of the hopping term and both considered coupling constants. It is evidenced that a nature and size of the further-neighbor Ising coupling between the localized spins basically influences rise and fall of reentrant transitions close to a phase boundary between the paramagnetic phase and both spontaneously ordered phases.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 1021-1023
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spontaneous Magnetization and Phase Diagrams of the Mixed Spin-1/2 and Spin-S Ising Model on the Bethe Lattice
Autorzy:
Strečka, J.
Ekiz, C.
Powiązania:
https://bibliotekanauki.pl/articles/1032659.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.50.+q
75.10.Hk
75.10.Kz
75.40.Cx
Opis:
The effect of uniaxial single-ion anisotropy on magnetic and critical properties of the mixed spin-1/2 and spin-S (S>1/2) Ising model on a three-coordinated Bethe lattice is rigorously examined with the help of star-triangle transformation and exact recursion relations. In particular, our attention is focused on the ferrimagnetic version of the model, which exhibits diverse temperature dependences of the total and both sublattice magnetizations. It is shown that the critical behavior of the mixed-spin Ising model on the Bethe lattice basically depends on whether the quantum spin number S is integer or half-odd-integer.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 615-617
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal Entanglement and Quantum Non-Locality along the Stepwise Magnetization Curve of the Spin-1/2 Ising-Heisenberg Trimerized Chain
Autorzy:
Strečka, J.
Pavličko, J.
Powiązania:
https://bibliotekanauki.pl/articles/1032512.pdf
Data publikacji:
2017-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Pq
75.10.Jm
75.40.Cx
75.60.Ej
Opis:
The spin-1/2 Ising-Heisenberg trimerized chain in a magnetic field is revisited with the aim to explore the quantum entanglement and non-locality within the exactly solved spin system, which exhibits in a low-temperature magnetization curve two intermediate plateaux at zero and one-third of the saturation magnetization. The ground-state phase diagram involves two quantum (antiferromagnetic, ferrimagnetic I) and two classical (ferrimagnetic II, saturated paramagnetic) phases. We have rigorously calculated the concurrence and Bell function in order to quantify the quantum entanglement and non-locality at zero as well as non-zero temperatures. It is demonstrated that the entanglement can be thermally induced also above the classical ground states unlike the quantum non-locality, which means that the thermal entanglement is indispensable for a violation of the locality principle.
Źródło:
Acta Physica Polonica A; 2017, 132, 1; 167-169
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ground State, Magnetization Process, and Magnetocaloric Effect of the Exactly Tractable Spin-Electron Tetrahedral Chain
Autorzy:
Gálisová, L.
Strečka, J.
Powiązania:
https://bibliotekanauki.pl/articles/1384829.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Pq
75.60.Ej
75.30.Sg
05.50.+q
Opis:
A hybrid spin-electron system on one-dimensional tetrahedral chain, in which the localized Ising spin regularly alternates with the mobile electron delocalized over three lattice sites, is exactly investigated using the generalized decoration-iteration transformation. The system exhibits either the ferromagnetic or antiferromagnetic ground state depending on whether the ferromagnetic or antiferromagnetic interaction between the Ising spins and mobile electrons is considered. The enhanced magnetocaloric effect during the adiabatic demagnetization suggests a potential use of the investigated system for low-temperature magnetic refrigeration.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 216-218
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Exact Ground States of Frustrated Spin-1 Ising-Heisenberg and Heisenberg Ladders in a Magnetic Field
Autorzy:
Strečka, J.
Michaud, F.
Mila, F.
Powiązania:
https://bibliotekanauki.pl/articles/1199503.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.50.+q
75.10.Jm
75.10.Kt
75.60.Ej
Opis:
Ground states of the frustrated spin-1 Ising-Heisenberg two-leg ladder with Heisenberg intra-rung coupling and only Ising interaction along legs and diagonals are rigorously found by taking advantage of local conservation of the total spin on each rung. The constructed ground-state phase diagram of the frustrated spin-1 Ising-Heisenberg ladder is then compared with the analogous phase diagram of the fully quantum spin-1 Heisenberg two-leg ladder obtained by density matrix renormalization group (DMRG) calculations. Both investigated spin models exhibit quite similar magnetization scenarios, which involve intermediate plateaux at one-quarter, one-half and three-quarters of the saturation magnetization.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 24-25
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kinetically-Driven Frustration in Hybrid Spin Ladders
Autorzy:
Carvalho, R.
Pereira, M.
Lyra, M.
Rojas, O.
Strecka, J
Powiązania:
https://bibliotekanauki.pl/articles/1199484.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Jm
75.10.Pq
05.70.Ce
Opis:
We introduce a spin ladder model incorporating localized and delocalized spins, which is exactly solvable using the decoration-iteration and transfer-matrix techniques. Quantum correlations between delocalized spins induce an antiferromagnetic coupling between the spin chains that competes with a direct ferromagnetic exchange coupling. A resulting kinetically-driven frustration is predominant in the regime of low temperatures and large hopping amplitudes. We provide the full ground-state phase diagram, as well as the frustration diagram on distinct coupling regimes.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 12-13
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Low-Temperature Thermodynamics of Spin-1/2 Orthogonal-Dimer Chain with Ising and Heisenberg Interactions
Autorzy:
Verkholyak, T.
Strečka, J.
Powiązania:
https://bibliotekanauki.pl/articles/1199501.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Jm
75.10.Pq
75.30.Gw
75.40.Cx
Opis:
We consider an exactly solvable version of the quantum spin-1/2 orthogonal-dimer chain with the Heisenberg intra-dimer and Ising inter-dimer couplings. The investigated quantum spin system exhibits at zero temperature fractional plateaux at 1/4 and 1/2 of the saturation magnetization and it has a highly degenerate ground state at critical fields where the magnetization jumps. We study the field dependence of the specific heat at low temperature. The lattice-gas description is formulated in a vicinity of critical fields to explain the low-temperature behaviour of specific heat.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 22-23
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetization Process and Adiabatic Demagnetization of the Antiferromagnetic Spin-1/2 Heisenberg Cubic Cluster
Autorzy:
Strečka, J.
Čisárová, J.
Powiązania:
https://bibliotekanauki.pl/articles/1366469.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Jm
75.30.Sg
75.40.Cx
75.50.Ee
75.60.Ej
Opis:
A full energy spectrum of the spin-1/2 Heisenberg cubic cluster is used to investigate a low-temperature magnetization process and adiabatic demagnetization of this zero-dimensional 2×2×2 quantum spin system. It is shown that the antiferromagnetic spin-1/2 Heisenberg cube exhibits at low enough temperatures a stepwise magnetization curve with four intermediate plateaux at zero, one quarter, one half, and three quarters of the saturation magnetization. We have also found the enhanced magnetocaloric effect close to level-crossing fields that determine transitions between the intermediate plateaux.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 26-27
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

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