arXiv subjects

Maxim M. Korovushkin

Publications and source records attributed to Maxim M. Korovushkin.

3 recordsLinked to original sources

arXiv2015

High-T$_c$ and Low-T$_c$ Superconductivity in Electron Systems With Repulsion

We demonstrate the instability of the normal state of purely repulsive fermionic systems towards the transition to the Kohn-Luttinger superconducting state. We construct the superconducting phase diagrams of these systems in the framework of the Hubbard and Shubin-Vonsovsky models on the square and hexagonal lattices. We show that an account for the long-range Coulomb interactions, as well as the Kohn- Luttinger renormalizations lead to an increase in the critical superconducting temperatures in various materials, such as high-temperature superconductors, idealized monolayer and bilayer of doped graphene. Additionally, we discuss the role of the structural disorder and the nonmagnetic impurities in superconducting properties of real graphene systems.

cond-mat.supr-con↗

arXiv2011

Kinematic formation of the pseudogap spectral properties in a spatially homogeneous strongly correlated electron system

It is shown that the kinematic interaction caused by the quasi-Fermi character of commutation relations for operators of the atomic representation can induce pseudogap behavior of the spectral characteristics of an ensemble of Hubbard fermions. Mathematically, the presence of the kinematic interaction manifests itself in modification of the faithful representation of a single-particle Green's function of Hubbard fermions $D(\textbf{k},iω_n)$, which involves, apart from self-energy operator $Σ_L(\textbf{k},iω_n)$, strength operator $P(\textbf{k},iω_n)$. It is important that the strength operator enters both the numerator and the denominator of the exact expression for $D(\textbf{k},iω_n)$. The kinematic interaction, therefore, not only renormalizes the spectrum of elementary excitations but significantly affects their spectral weight. It results in strong modulation of spectral intensity $A(\textbf{k},ω)$ occurring on a Fermi contour. Calculations of the spectral properties for the $t-J$ model in the one-loop approximation yield good quantitative agreement with the ARPES data obtained on cuprate superconductors.

cond-mat.str-el↗

arXiv2009

Hubbard fermions band splitting at the strong intersite Coulomb interaction

The effect of the strong intersite Coulomb correlations on the formation of the electron structure of the t-V-model has been studied. A qualitatively new result has been obtained which consists in the occurrence of a split-off band of the Fermi states. The spectral intensity of this band increases with the enhancement of a doping level and is determined by the mean-square fluctuation of the occupation numbers. This leads to the qualitative change in the structure of the electron density of states.

cond-mat.str-el↗