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The theory of conductivity of rare earth compounds and polyenes is constructed on the basis of the fluctuational theory of magnetic superconductors. The criterion of the appearance of the high-temperature superconducting phase in rare earth antiferromagnetic compounds and of the superconductivity in polyene systems is found. 相似文献
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A new class of materials is constructed of rare earth metals and their compounds by introduction of a large number of defects into the crystal lattice-dislocations and unelastic disclinations. It is shown that superconductive phase state is possible in these materials having spin glass magnetic structure. A technique of such a state observation is suggested. 相似文献
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V. R. Shaginyan A. Z. Msezane G. S. Japaridze V. A. Stephanovich Y. S. Leevik 《JETP Letters》2018,108(5):335-340
Tunneling differential conductivity (or resistivity) is a sensitive tool to experimentally test the non-Fermi liquid behavior of strongly correlated Fermi systems. In the case of common metals the Landau–Fermi liquid theory demonstrates that the differential conductivity is a symmetric function of bias voltage V. This is because the particle–hole symmetry is conserved in the Landau–Fermi liquid state. When a strongly correlated Fermi system turns out to be near the topological fermion condensation quantum phase transition, its Landau–Fermi liquid properties disappear so that the particle–hole symmetry breaks making the differential tunneling conductivity to be asymmetric function of V. This asymmetry can be observed when a strongly correlated metal is in its normal, superconducting or pseudogap states. We show that the asymmetric part of the dynamic conductance does not depend on temperature provided that the metal is in its superconducting or pseudogap states. In normal state, the asymmetric part diminishes at rising temperatures. Under the application of magnetic field the metal transits to the Landau–Fermi liquid state and the differential tunneling conductivity becomes a symmetric function of V. These findings are in good agreement with recent experimental observations. 相似文献
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M. D. Glinchuk E. A. Eliseev V. A. Stephanovich B. Hilczer 《Physics of the Solid State》2001,43(7):1299-1306
A model based on the random-field theory is proposed for calculating the properties of solid solutions of ferroelectric relaxors. The electric dipoles randomly distributed in the system are treated as sources of random fields. The random field distribution function is calculated taking into account the contribution of nonlinear and correlation effects and the differences in the dipole orientations for different solid solution components. The dependence of the phase transition temperature T c on the concentration of solid solution components is analyzed. Numerical calculations are performed for the lead scandoniobate and lead scandotantalate solid solutions (PbSc1/2Nb1/2O3)1?x (PbSc1/2Ta1/2O3)x with different degrees of ordering and the lead magnoniobate and lead titanate solid solution (PbMg1/3Nb2/3O3)1?x (PbTiO3)x. It is shown that the higher transition temperature for more disordered solid solutions of the composition (PbSc1/2Nb1/2O3)1?x (PbSc1/2Ta1/2O3)x in the range 0≤x<0.5 is associated with the larger nonlinearity coefficient for PbSc1/2Nb1/2O3 as compared to that for PbSc1/2Ta1/2O3. The theory provides a means for calculating the region of the coexistence of the phases with different symmetry groups in the temperature-composition phase diagram of the (PbMg1/3Nb2/3O3)1?x (PbTiO3) solid solution. Numerical calculations with the use of the fitting parameters obtained from the known transition temperatures T c for the solid solution components adequately describe the experimental phase diagrams for the aforementioned solid solutions of ferroelectric relaxors. 相似文献
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The microscopic theory of the superconductive phase in rare earth metal compounds is constructed by contour averages mathematical method. It is shown that in the superconductive phase the effect of exchange intensification occurs and the promotion of superconductive phase transition temperature is possible. 相似文献
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V. R. Shaginyan;A. Z. Msezane;K. G. Popov;G. S. Japaridze;V. A. Stephanovich 《Europhysics letters》2012,97(5)
An exotic quantum spin liquid (QSL) is formed with such hypothetic particles as fermionic spinons carrying spin 1/2 and no charge. Here we calculate its thermodynamic and relaxation properties. Our calculations unveil the fundamental properties of QSL, forming a strongly correlated Fermi system located at a fermion condensation quantum phase transition. These are in good agreement with experimental data and allow us to detect the behavior of QSL as that observed in heavy-fermion metals. We predict that the thermal resistivity of QSL under the application of magnetic fields at fixed temperature demonstrates a very specific behavior. The key features of our findings are the presence of spin-charge separation and QSL formed with itinerant heavy spinons in herbertsmithite.https://doi.org/10.1209/0295-5075/97/56001 相似文献
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We predict that spin-waves in an easy-plane ferromagnet have a finite lifetime at zero temperature due to spontaneous decays. In zero field the damping is determined by three-magnon decay processes, whereas decays in the two-particle channel dominate in a transverse magnetic field. Explicit calculations of the magnon damping are performed in the framework of the spin-wave theory for the XXZ square-lattice ferromagnet with an anisotropy parameter λ<1. In zero magnetic field the decays occur for λ*<λ<1 with λ*≈1/7. We also discuss the possibility of experimental observation of the predicted effect in a number of ferromagnetic insulators.https://doi.org/10.1209/0295-5075/95/17007 相似文献
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The microscopic theory of the superconductive phase in rare earth metal compounds is constructe by the contour averages mathematical method. It is shown that in the superconductive phase thd effect of exchange intensification occurs and increase of superconductive phase transition tempere ature is possible. 相似文献
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