Effect of Magneto-Pulse Processing on the Microstructure and Magnetic Behavior of Amorphous Electrotechnical Steel

The effect of magneto-pulse processing on the microstructure and magnetic behavior of amorphous electrotechnical steel is studied. It is found that the directed ordering of Fe atoms helps to increase specific magnetization of saturation and the coefficient of the squareness of the hysteresis loop, and is related to ordering of the spin system.     

Phase diagram of the Kohn-Luttinger superconducting state for bilayer graphene

The effect of Coulomb interaction between Dirac fermions on the formation of the Kohn-Luttinger superconducting state in bilayer doped graphene is studied disregarding of the effect of the van der Waals potential of the substrate and impurities. The phase diagram determining the boundaries of superconductive domains with different types of symmetry of the order parameter is built using the extended Hubbard model in the Born weak-coupling approximation with allowance for the intratomic, interatomic, and interlayer Coulomb interactions between electrons. It is shown that the Kohn-Luttinger polarization contributions up to the second order of perturbation theory in the Coulomb interaction inclusively and an account for the long-range intraplane Coulomb interactions significantly affect the competition between the superconducting phases with the f-, p + ip-, and d + id-wave symmetries of the order parameter. It is demonstrated that the account for the interlayer Coulomb interaction enhances the critical temperature of the transition to the superconducting phase.     

Study of Features of the Composition,Magnetic, and Crystal Structure of Barium Hexaferrite BaFe12 – xTixO19

Physics of the Solid State - The features of the composition, crystal, and magnetic structure of Ti-substituted barium hexaferrite BaFe12 – xTixO19 (0.25 ≤ x ≤...     

Features of the Magnetic Structure of Y3Fe5O12 Polycrystals Synthesized by Radiation Thermal Sintering

Physics of the Solid State - Samples of polycrystalline yttrium-iron garnet synthesized using radiation-thermal sintering and ceramic processing have been studied by the Mössbauer spectroscopy...     

Nucleophilic substitution in ethyl fluorosulfonoxydifluoroacetate

Conclusions Ethyl fluorosulfonoxydifluoroacetate undergoes nucleophilic replacement with the formation of derivatives of difluoroacetic acid. The reaction with fluoride anion mainly features cleavage of the S-O bond leading to the acid fluoride of the monoethyl ester of oxalic acid.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1435–1437, June, 1985.     

Effective interactions and the nature of Cooper instability of spin polarons in the 2D Kondo lattice

It has been shown that two-and three-center interactions arise in the strong-coupling regime for the 2D Kondo lattice; these interactions both induce and suppress the Cooper instability. It is important that, in contrast to the t-J* model, the three-center interactions promote the Cooper pairing and ensure the appearance of the superconducting phase with a high critical temperature T _c. The calculated concentration dependences of T _c agree well with the experimental data for the cuprate superconductors.     

Coulomb repul sion of hole s and competition between $${d_{{x^2} - {y^2}}}$$ -wave and s-wave paring s in cuprate superconductor s

The effect of the Coulomb repulsion of holes on the Cooper instability in an ensemble of spin–polaron quasiparticles has been analyzed, taking into account the peculiarities of the crystallographic structure of the CuO₂ plane, which are associated with the presence of two oxygen ions and one copper ion in the unit cell, as well as the strong spin–fermion coupling. The investigation of the possibility of implementation of superconducting phases with d-wave and s-wave of the order parameter symmetry has shown that in the entire doping region only the d-wave pairing satisfies the self-consistency equations, while there is no solution for the s-wave pairing. This result completely corresponds to the experimental data on cuprate HTSC. It has been demonstrated analytically that the intersite Coulomb interaction does not affect the superconducting d-wave pairing, because its Fourier transform V _q does not appear in the kernel of the corresponding integral equation.     

Features of the Cation Distribution and Magnetic Properties of BaFe12 − xYxO19 Hexaferrites

Physics of the Solid State - Using Mössbauer spectroscopy, magnetometry and X-ray diffraction, we have studied the BaYxFe12 – xO19 hexaferrite (0.1 ≤ x ≤...     

Lower subband splitting and superconductivity of 2D Hubbard fermions with strong intersite correlations

The effect of the strong intersite Coulomb correlations on the formation of an electron structure in the Shubin-Vonsowsky model in the regime of strong one-site correlations is studied. The results reveal a split-off band of the Fermi states. The spectral intensity of this band grows with the enhancement of the doping level and is determined by the mean-square fluctuation of occupation numbers. This changes the structure of the electron density of states qualitatively.     

The effective Hamiltonian for copper oxides

The concentration dependence of the exchange integral for the subsystem of spin moments of copper ions J(h) = J ? J ₁ × h ? J ₂ × h ² has been calculated for the Emery model within the effective Hamiltonian obtained with due regard to intersite interactions and oxygen configurations with different numbers of holes. It is shown that allowance for the oxygen single-hole states occurring upon doping leads to additional contributions to J(h), whose intensities depend on the intersite correlations of the nearest environment of exchange-coupled copper ions.