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1.
E. V. Kuz’min S. G. Ovchinnikov I. O. Baklanov 《Journal of Experimental and Theoretical Physics》1999,89(2):349-357
We propose a t-J-I model with direct ferromagnetic exchange I to explain the superconductivity of copper oxides and the ruthenate Sr2RuO4 on the basis of the analysis of the electronic structure of these substances. We analyze the possible p-and d-type superconducting solutions. Solutions of the s type with singlet pairings are impossible in the strong-electron-correlations regime, and p-type solutions correspond to triplet superconductivity and is formed near the ferromagnetic instability threshold in ruthenates.
The solution with the
symmetry near the antiferromagnetic instability threshold corresponds to copper oxides. We also discuss the reason for the
high values of the superconducting transition temperature (T
c
∼100 K) in copper oxides and the low values (T
c
∼1 K) in ruthenates.
Zh. éksp. Teor. Fiz. 116, 655–670 (August 1999) 相似文献
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The voltage relaxation of galvanic cells with zirconia based electrolytes polarised between an inert Pt electrode and a Pt/air
electrode is analysed to obtain the diffusion coefficients of holes and electrons. The hole diffusion coefficient can be reduced
by replacing zirconium with guest ions of different size, e.g. Nb5+ and Ti4+. The TZP phase with 3 mol% Y2O3 of dopant has a higher hole diffusion coefficient than the CYZ phase doped with 8 mol% Y2O3. 1 and 3 mol% p-type MnO1.5 doping increases the conductivity of holes in CYZ to a large extend, but does not influence the diffusivity. This indicates
that the doping increases the hole conductivity through an increased concentration of holes. In the case of 10 and 15 mol%
MnO1.5 doped Z3Y, the electronic conductivity is dominant. The chemical diffusion coefficients which are related to the oxygen vacancies
were determined by GITT. The results show that the chemical diffusion coefficient of oxygen vacancies is much larger than
that for holes in zirconia. 相似文献
4.
A. S. Moskvin 《Optics and Spectroscopy》2011,111(3):403-410
The cluster model of p-d and d-d charge-transfer transitions in strongly correlated 3d oxides is briefly reviewed. The application of this model is illustrated by an analysis of experimental optical spectra of
orthorhombic manganites of the LaMnO3 type. 相似文献
5.
The evolution of the magnetic and kinetic properties of quasi-two-dimensional cuprates has been studied upon doping CuO2 planes with electron holes. The notion of thermal skyrmions and hole-induced skyrmions was used to determine the spin-correlation length and nuclear relaxation rate as functions of temperature and hole concentration. 相似文献
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Zaliznyak IA Woo H Perring TG Broholm CL Frost CD Takagi H 《Physical review letters》2004,93(8):087202
We have investigated the spin dynamics in the strongly correlated chain copper oxide SrCuO2 for energies up to greater, similar 0.6 eV using inelastic neutron scattering. We observe a gapless continuum of magnetic excitations, which is well described by the "Müller ansatz" for the two-spinon continuum in the S=1/2 antiferromagnetic Heisenberg spin chain. The lower boundary of the continuum extends up to approximately 360 meV, which corresponds to an exchange constant J=226(12) meV. 相似文献
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A. P. Tyutnev V. S. Saenko E. P. Grach E. D. Pozhidaev 《Russian Journal of Physical Chemistry B, Focus on Physics》2010,4(2):346-349
The dependence of the mobility of charge carriers in molecularly doped polycarbonate on the thickness of the polymer was studied
at two dopant DEH concentrations (30 and 50 wt %). The mobility of holes in the more concentrated polymer did decrease as
the film thickness increased in close agreement with the predictions of the theory of weakly nonequilibrium transport with
a dispersion parameter of 0.75. For films with a lower dopant concentration, such a categorical statement cannot be made,
because mobility can either decrease as the film thickness increases or remain almost unchanged depending on the method for
data processing. For this reason, it is not recommended to use the dependence of the time of flight on film thickness as a
criterion for selecting the mechanism of the transport of charge carriers in molecularly doped polymers. 相似文献
13.
We show that the semiclassical model of conduction breaks down if the mean free path of charge carriers is smaller than a typical extension of their wave function. This situation is realized for sufficiently slow charge carriers and leads to a transition from a metalliclike to an insulatinglike regime when scattering by defects increases. This explains the unconventional conduction properties of quasicrystals and related alloys. The conduction properties of some heavy fermions or polaronic systems, where charge carriers are also slow, present a deep analogy. 相似文献
14.
E. I. Shneyder S. G. Ovchinnikov 《Journal of Experimental and Theoretical Physics》2009,109(6):1017-1021
Peculiarities of the temperature isotope effect in a BCS-type theory describing the exchange and phonon mechanisms of Cooper
pairing in a system of strongly correlated electrons are considered. The electron-phonon interaction constant is determined
from the fitting of the calculated value of the isotope-effect index to the observed value with the parameters of La2 − x
Sr
x
CuO4 obtained from ab initio calculations. The value of this constant indicates that the contribution from the traditional pairing
mechanism to the superconducting state is of the same order of magnitude as the contribution from the magnetic mechanism. 相似文献
15.
Kh. G. Bogdanova A. R. Bulatov V. A. Golenishchev-Kutuzov A. A. Potapov 《Bulletin of the Russian Academy of Sciences: Physics》2012,76(7):826-828
The mutual influence of ferromagnetic and Jahn-Teller ordering in weakly doped manganites with the content La1 ? x Sr x MnO3 (0.17 < x < 0.175) is considered. A phenomenological explanation of colossal magnetic resistance based on suppression of the local Jahn-Teller structure of distorted MnO6 octahedrons by means of an applied magnetic field is suggested. 相似文献
16.
Yu. B. Kudasov 《Physics of the Solid State》2001,43(8):1552-1555
A new variational method is used to investigate the ground state of the Hubbard model with a half-filled band for a one-dimensional chain, a planar square lattice, and a simple cubic lattice. A metamagnetic transition is found to occur in a one-dimensional chain and a simple square lattice. A simple cubic lattice does not undergo the metamagnetic transition. 相似文献
17.
We investigate the magnetic properties of archetypal transition-metal oxides MnO, FeO, CoO, and NiO under very high pressure by x-ray emission spectroscopy at the Kbeta line. We observe a strong modification of the magnetism in the megabar range in all the samples except NiO. The results are analyzed within a multiplet approach including charge-transfer effects. The spectral changes are well accounted for by changes of the ligand field acting on the d electrons and allows us to extract the d-hybridization strength, O-2p bandwidth and ionic crystal field across the magnetic transition. This approach allows first-hand insight into the mechanism of the pressure-induced spin transition. 相似文献
18.
W.-H. Steeb 《Physics letters. A》1975,55(7):433-434
Using a doubly degenerate Hubbard model we derive an effective Hamiltonian in the limiting case where the Coulomb repulsion is much greater than the hopping constant. A brief discussion of this Hamiltonian is given. 相似文献
19.
The effective Hamiltonian for a realistic multiband p-d model is developed. In the case of electron doping, the Hamiltonian coincides with that for the standard t-J model. For hole doping, the singlet-triplet t-J model takes place. 相似文献
20.
Relaxation and dynamics of charge carriers in organic polymer semiconductors: Polyacetylene (review)
V. I. Krinichnyi 《Physics of the Solid State》1997,39(1):1-13
The results of investigations of cis-polyacetylene and trans-polyacetylene by EPR spectroscopy in the 2-mm wave range are
systematized and generalized. The nature and dynamic properties of nonlinear soliton-type carriers are discussed, along with
the charge transfer mechanism in neutral polyacetylene.
Fiz. Tverd. Tela (St. Petersburg) 39, 3–17 (January 1997) 相似文献