Full-text resources of PSJD and other databases are now available in the new Library of Science.
Visit https://bibliotekanauki.pl
Preferences help
Polish version English version Language
enabled [disable] Abstract
Number of results

Results found: 5

Number of results on page
first rewind previous Page / 1 next fast forward last

Search results

help Sort By:

help Limit search:
first rewind previous Page / 1 next fast forward last
1
Content available remote

Field-Dependent Specific Heat and Energy Gap in the Yb_4As_3 Compound

100%
Matysiak R.
|
|
issue 5
969-970
EN
We report the low-temperature specific-heat simulation results and reanalyzed measurement data on polydomain Yb_4As_3 in magnetic fields B = 0 and 6 T. The data considered here are independent and supplement those considered earlier. A quantitative agreement has again been achieved between the magnetic experimental specific-heat data and the numerical results obtained by the quantum transfer-matrix simulation technique, yielding a new evidence in favour of the Heisenberg model of the antiferromagnetic spin S = 1/2 chain with the value of the exchange integral J/k_{B} = - 28 K. The finite-size quantum transfer matrix approximants have been extrapolated exploiting the procedure developed previously. On the basis of the data in magnetic field and using the corresponding density-matrix renormalization group results, the energy-gap size Δ has been estimated for the applied magnetic field B = 6 T, leading to the experimental verification in the extended region of the scaling law Δ ∿ B^{2/3} following from the sine-Gordon model.
2
Content available remote

Transfer-Matrix Simulations of Linear Magnetic Systems

51%
Matysiak R., Caramico D'Auria A., Esposito F., Esposito U.
Acta Physica Polonica A
|
2000
|
vol. 97
|
issue 5
959-962
EN
The quantum transfer-matrix method was applied to study the finite-temperature static properties of the spin S=1 antiferromagnetic Heisenberg chains in a wide range of the single-ion anisotropy and temperatures. The high-resolution quantum transfer-matrix simulation data are obtained for the zero-field susceptibility, specific heat as well as for the field-dependent magnetization. The microscopic parameters of a number of real quasi-one-dimensional compounds are found from fitting procedures, some theoretical approaches are numerically verified and an extension of the technique to a non-uniform bond alternating molecular magnets is also put forward.
3
Content available remote

Numerical Simulations of Linear S=1 Ferro- and Antiferromagnets

45%
Kamieniarz G., Matysiak R., Caramico D'Auria A., Esposito F., Esposito U.
Acta Physica Polonica A
|
1997
|
vol. 92
|
issue 2
387-389
EN
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.
4
Content available remote

Some Mesoscopic Rings: Exact Simulations and Experiment

45%
Kamieniarz G., Matysiak R., D'Auria A. C., Esposito F., Benelli C.
Acta Physica Polonica A
|
2000
|
vol. 98
|
issue 6
721-727
EN
A numerical transfer-matrix approach and an exact diagonalization technique exploiting the point-group symmetry are worked out in the framework of quantum statistical mechanics and group theory for finite rings. They are applied to spin models of the high nuclearity cyclic clusters [Mn(hfac)_{2}NITPh]_{6} and Ni_{12}(O_{2}CMe)_{12}(chp)_{12}(H_{2}O)_{6}(THF)_{6}. The microscopic parameters of both molecules (J/k_{B}=350±10 K and J/k_{B}=8.5 K±0.5, g=2.23±0.01, respectively) are then obtained from a fit of the theoretical susceptibility curves to the experimental results which are supplemented for Ni_{12} by new low-temperature measurements.
5
Content available remote

DMRG Approach to a Molecular-Based Bimetallic Chain Containing Re(IV) and Cu(II) Ions

39%
Sobczak P., Barasiński A., Matysiak R., Drzewiński A., Kamieniarz G., Bieńko A., Mroziński J.
|
|
issue 5
975-977
EN
The bimetallic chain complex [Cu(tren)]ReCl_6 is numerically analysed on the basis of the anisotropic quantum Heisenberg model without the mean-field corrections by the density-matrix renormalization group approach. The high accuracy results of our simulations have been fitted to the corresponding experimental susceptibility data above the crossover regime. The set of model parameters comprising the strength of antiferromagnetic couplings, the single-ion anisotropy term and the corresponding g factors have been found: J/k_{B} = 3.5 ± 0.5 K, D/k_{B} = 35 ± 5 K, g_{Cu} = 2.07 ± 0.05 and g_{Re} = 1.73 ± 0.01.
first rewind previous Page / 1 next fast forward last
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.