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11.
M. Yu. Kagan V. V. Val’kov V. A. Mitskan M. M. Korovushkin 《Journal of Experimental and Theoretical Physics》2014,118(6):995-1011
We present a review of theoretical investigations into the Kohn-Luttinger nonphonon superconductivity mechanism in various 3D and 2D repulsive electron systems described by the Fermi-gas, Hubbard, and Shubin-Vonsovsky models. Phase diagrams of the superconducting state are considered, including regions of anomalous s-, p-, and d-wave pairing. The possibility of a strong increase in the superconducting transition temperature T c even for a low electron density is demonstrated by analyzing the spin-polarized case or the two-band situation. The Kohn-Luttinger theory explains or predicts superconductivity in various materials such as heterostructures and semimetals, superlattices and dichalcogenides, high-T c superconductors and heavy-fermion systems, layered organic superconductors, and ultracold Fermi gases in magnetic traps. This theory also describes the anomalous electron transport and peculiar polaron effects in the normal state of these systems. The theory can be useful for explaining the origin of superconductivity and orbital currents (chiral anomaly) in systems with the Dirac spectrum of electrons, including superfluid 3He-A, doped graphene, and topological superconductors. 相似文献
12.
It has been shown in the limit of the low density of band carriers that the inclusion of the strong intersite interaction between electrons within the framework of the periodic Anderson model results in two qualitatively new features in its energy structure. The first feature is associated with the appearance of an additional quasi-localized level, which significantly changes the structure of the electronic density of states. The second feature is the strong renormalization of the effective constant of hybridization with the bare localized level. 相似文献
13.
The problem of Cooper instability is studied by implementing the Kohn-Luttinger mechanism in the framework of the Shubin-Vonsowsky model taking into account the intersite Coulomb interactions within the first and second coordination spheres. It is shown that the Kohn-Luttinger renormalization for the effective interaction in the second-order terms of perturbation theory, as well as the inclusion of intersite hoppings in the second and third coordination spheres, significantly affects the interplay between the superconducting phases with d xy -, p-, s-, and $d_{x^2 - y^2 }$ -wave symmetries of the order parameter. 相似文献
14.
The influence of spin and charge fluctuations on the pseudogap formation in cuprate superconductors has been studied using
the diagram technique for Hubbard operators. It has been shown that the joint inclusion of the spin and charge fluctuations
leads to the formation of “shadow” bands with a strong modulation of the spectral intensity and to a decrease in the density
of electronic states at the Fermi level. 相似文献
15.
M. N. Shipko V. V. Korovushkin V. G. Kostishin I. M. Isaev M. A. Stepovich E. S. Savchenko 《Bulletin of the Russian Academy of Sciences: Physics》2018,82(2):203-207
The effect a pulsed magnetic field has on the crystal structure and macroscopic magnetic parameters of hexagonal ferrites BaFe12O19 and SrFe12O19 are studied. It is shown that changes in the physical properties of ferrites are due to the ordering of cation vacancies on the boundaries of hexagonal and spinel blocks that minimize local distortion of the oxygen polyhedrons. Violation of the collinear ordering of the magnetic moments of iron ions in the nonequivalent positions of SrFe12O19 ferrite is observed, due to the selective localization of such vacancies (and thus violations of the magnetic relationships in Fe–O–Fe). 相似文献
16.
Magnetic and Radio-Absorbing Properties of Polycrystalline Li0.33Fe2.29Zn0.21Mn0.17O4 Spinel Ferrite
Isaev I. M. Kostishin V. G. Korovushkin V. V. Salogub D. V. Shakirzyanov R. I. Timofeev A. V. Mironovich A. Yu. 《Technical Physics》2021,66(11):1216-1220
Technical Physics - Polycrystalline spinel ferrites with a composition of Li0.33Fe2.29Zn0.21Mn0.17O4 have been synthesized using the ceramic technology at sintering temperatures of 950, 1000, 1050,... 相似文献
17.
V. V. Val’kov M. M. Korovushkin 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,69(2):219-227
The effect of the intersite Coulomb interaction of fermions on the ground state and energy structure of high-temperature superconductors
is considered within the three-band Emery model using an extended basis of the irreducible operators orthogonal on Mori. The
proposed theory allows prediction of bands of the fluctuation states whose spectral intensity grows with an increase in the
root-mean-square fluctuations of the occupation numbers. The increase in these fluctuations in high-temperature superconductors
upon doping plays a key role in redistribution of the integrated density of the Fermi states. 相似文献
18.
A. V. Trukhanov V. G. Kostishin V. V. Korovushkin L. V. Panina S. V. Trukhanov V. A. Turchenko I. S. Polyakov R. Kh. Rakhmatullin G. A. Filatov T. I. Zubar’ V. V. Oleinik E. S. Yakovenko L. Yu. Matsui L. L. Vovchenko V. L. Launets E. L. Trukhanova 《Physics of the Solid State》2018,60(9):1768-1777
The correlation of the chemical composition, the structure, and the microwave characteristic of solid solutions of the BaFe12 – xDxO19 (0.1 ≤ x ≤ 1.2) barium hexaferrite substituted with diamagnetic Al3+ and In3+ ions has been studied. The precise data on the crystal structure have been obtained by powder neutron diffraction using a high-resolution Fourier diffractometer (Dubna, JINR). The data on the distribution of the diamagnetic substituting ions in the hexaferrite structure have been obtained by Mössbauer spectroscopy. The microwave properties (the transmittance and the reflectance) have been studied in the frequency range 20–65 GHz and in external magnetic fields to 8 kOe. It is found that the transmission spectra are characterized by a peak that corresponds to the resonant frequency of the electromagnetic energy absorption, which is due to the ferromagnetic resonance phenomenon. The correlation of the chemical composition, the features of the ion distribution in the structure, and the electromagnetic properties has been revealed. It is shown that external magnetic fields shift the absorption peak of electromagnetic radiation to higher frequencies due to an increase in the magnetocrystal anisotropy. The results enable the conclusion that the features of the intrasublattice interactions and the electromagnetic properties should be explained using the phenomenological Goodenough–Kanamori model. 相似文献
19.
M. N. Shipko V. G. Kostishin M. A. Stepovich V. V. Korovushkin 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2017,11(1):142-145
The influence of treatment in corona discharge plasma on the magnetic properties of BaFe12O19 single- and polycrystalline ferrites, as well as structural-chemical transformations in their crystal lattices, are studied. The revealed dependence between structural-sensitive microscopic parameters and the duration of corona-discharge-plasma treatment indicates the manifestation of the corona-electret effect in BaFe12O19 single crystals. 相似文献
20.
V. V. Val’kov A. A. Shklyaev M. M. Korovushkin A. F. Barabanov 《Physics of the Solid State》2011,53(10):1997-2000
The normal and superconducting phases of the ensemble of spin polarons in a two-dimensional Kondo lattice have been considered
under the conditions when the hopping integral is comparable to the s-d exchange interaction energy. The polaron excitation spectrum and the superconducting transition temperature have been found
taking into account upper triplet states. The change in the concentration dependence of the critical temperature of the transition
to the superconducting phase with the relation between the hopping integral and the integral of the s-d exchange coupling has been analyzed. 相似文献