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Tytuł:
Orbital Correlations in Monolayer Manganites - From Spin t-J Model to Orbital t-J Model
Autorzy:
Daghofer, M.
Oleś, A. M.
Powiązania:
https://bibliotekanauki.pl/articles/2047308.pdf
Data publikacji:
2007-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Jm
75.30.Et
75.47.Lx
Opis:
On the example of monolayer manganites we show that the theoretical ideas developed long ago along the derivation of the spin t-J model from the Hubbard model are nowadays very helpful in strongly correlated oxides with partly filled degenerate orbitals. We analyze a realistic orbital t-J model for e$\text{}_{g}$ electrons in La$\text{}_{1-x}$Sr$\text{}_{1+x}$MnO$\text{}_{4}$ monolayer manganites, and discuss the evolution of spin and orbital correlations under increasing doping by performing exact diagonalization of finite clusters, with electronic kinetic energy determined self-consistently at a finite temperature by classical Monte Carlo for t$\text{}_{2g}$ spins. Several experimental results are reproduced.
Źródło:
Acta Physica Polonica A; 2007, 111, 4; 497-512
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An Extended Supersymmetric t-J Model
Autorzy:
Zhang, Yao-Zhong
Powiązania:
https://bibliotekanauki.pl/articles/1943941.pdf
Data publikacji:
1995-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.Ad
75.10.Jm
Opis:
A new lattice model is presented for correlated electrons on the unrestricted 4$\text{}^{L}$-dimensional electronic Hilbert space ⨁$\text{}_{n=1}^{L}$C$\text{}^{4}$ (where L is the lattice length). It is an extension of the supersymmetric t-J model. The new model has gl(2|1) supersymmetry and contains one symmetry-preserving free real parameter α which has its origin in the one-parameter family of inequivalent typical 4-dimensional irreps of gl(2|1). When α = 0, the model reduces to the supersymmetric t-J model.
Źródło:
Acta Physica Polonica A; 1995, 88, 6; 1119-1122
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Critical Values for Electron Pairing in t-U-J-V and t-J-V Models
Autorzy:
Bak, M.
Powiązania:
https://bibliotekanauki.pl/articles/1812342.pdf
Data publikacji:
2008-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.-z
74.20.Fg
74.20.Rp
74.25.Dw
71.10.Fd
71.27.+a
Opis:
The critical values for pairing of s*- and d-wave symmetry are calculated within the t-U-J-V and the t-J-V models in renormalized mean field theory. It is shown that the first model yields the proper critical values in the low density limit while the other does not. Renormalized mean field theory strongly decreases the absolute value of (negative) critical values for larger electron densities.
Źródło:
Acta Physica Polonica A; 2008, 114, 1; 275-279
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The t-J Model in a Strong Magnetic Field
Autorzy:
Sherman, A.
Powiązania:
https://bibliotekanauki.pl/articles/1384828.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.Fd
71.27.+a
71.70.Di
74.72.Gh
Opis:
The normal-state energy spectrum of the two-dimensional t-J model in a homogeneous perpendicular magnetic field B is investigated using the Mori projection operator technique. The density of states at the Fermi level as a function of 1/B reveals both high- and low-frequency oscillations. The high-frequency oscillations correspond to large Fermi surfaces, while the low-frequency components are related to van Hove singularities in the Landau subbands, which stem from their bending due to strong electron correlations. Frequencies of the low-frequency components are of the same order of magnitude as those observed in underdoped cuprates. These components become dominant if smoothing processes are involved. It is shown that despite increased distances between subbands the pseudogap affects only slightly the frequency of density of states oscillations.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 213-215
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Phases and Generalized t-J Models in Doped Mott-Hubbard Insulators
Autorzy:
Oleś, A. M.
Zaanen, J.
Powiązania:
https://bibliotekanauki.pl/articles/1861025.pdf
Data publikacji:
1994-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.-h
64.60.-i
64.90.+b
75.40.-s
Opis:
We review some recent results obtained for the dynamics of a single hole and for the ground states at finite hole doping in t-J model. Next, we address the role of orbital degeneracy in doped Mott-Hubbard insulators and show examples of effective strong coupling models which include the orbital degrees of freedom. These new t-J models have interesting phase diagrams, with the new magnetic phases stabilized by a competition between magnetic energy and excitonic excitations. It is argued that the doped holes always bind to the excitons and that the new phases identified on the mean-field level give rise to local distortions of the lattice. We conclude that realistic t-J models derived from the electronic structure of particular compounds may be successfully applied for understanding both the observed magnetic ground states, and the results of photoemission experiments, as we have demonstrated recently for NiO.
Źródło:
Acta Physica Polonica A; 1994, 85, 1; 145-163
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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