Related papers: A phenomenological multiband Eliashberg model for …
We investigate theoretically the superconducting state of the undoped Fe-based superconductor ThFeAsN. Using input from $ab~initio$ calculations, we solve the Fermi-surface based, multichannel Eliashberg equations for Cooper-pair formation…
Based on BCS model with the external pair potential formulated in a work Grigorishin (2017) [1], analogous model with electron-phonon coupling and Coulomb coupling is proposed. The generalized Eliashberg equations in the regime of…
Weak-coupling expansions (conserving approximations) are carried out for the attractive Holstein and Hubbard models (on an infinite-dimensional hypercubic lattice) that include all bandstructure and vertex correction effects. Quantum…
We present here a microscopic two-band model based on the structure of energetic levels of holes in $\mathrm{CuO}_{2}$ conducting layers of cuprates. We prove that two energetically near-lying interacting bands can explain the electron-hole…
Eliashberg - McMillan theory of superconductivity is essentially based on the adiabatic approximation. Small parameter of perturbation theory is given by $\lambda\frac{\Omega_0}{E_F}\ll 1$, where $\lambda$ is the dimensionless electron -…
Anomalously large fluctuation diamagnetism around the superconducting critical temperature has been recently observed on iron selenide (FeSe) [S. Kasahara et al., unpublished]. This indicates that superconducting fluctuations (SCFs) play a…
Using the microscopic formalism of Eilenberger equations, a three-band Ginzburg-Landau theory for the intraband dirty limit and clean interband scattering case is derived. Within the framework of this three-band Ginzburg-Landau theory,…
Starting from an {\it ab initio}-derived two-site dimer Hubbard hamiltonian on a triangular lattice, we calculate the superconducting gap functions and critical temperatures for representative $\kappa$-(BEDT-TTF)$_2$X superconductors by…
The semi-classical Lifshitz-Kosevich (LK) description of quantum oscillations is extended to a multiband two-dimensional Fermi liquid with a constant number of electrons. The amplitudes of novel oscillations with combination frequencies,…
Observation of robust superconductivity in some of the iron based superconductors in the vicinity of a Lifshitz point where a spin density wave instability is suppressed as the {hole} band drops below the Fermi energy raise questions for…
We present a scenario for iron-pnictide superconductivity mediated by charge fluctuations that are strongly enhanced by Fe-As intersite electronic interactions. Deriving an eight-band extended Hubbard model including Fe 3$d$ and As 4$p$…
A comprehensive theory is developed that describes the coexistence of p-wave, spin-triplet superconductivity and itinerant ferromagnetism. It is shown how to use field-theoretic techniques to derive both conventional strong-coupling theory,…
We demonstrate that many features ascribed to strong correlation effects in various spectroscopies of the cuprates are captured by a calculation of the self-energy incorporating effects of spin and charge fluctuations. The self energy is…
Using the quasi-classical formalism we provide the description of the temperature and field-direction dependence of the in-plane upper critical field in layered superconductors, taking into account the interlayer Josephson coupling and the…
We formulate and solve the Eliashberg equations on the imaginary frequency axis at temperatures below $T_c$ in the weak-coupling limit. We find an excellent scaling at all temperatures, for a given coupling strength, and the normalized…
In this paper we address Lifshitz transition induced by applied external magnetic field in a case of iron-based superconductors, in which a difference between the Fermi level and the edges of the bands is relatively small. We introduce and…
Experimentally relevant signatures of superconductivity require access to real-frequency quantities, such as the spectral functions, optical response, and transport properties, yet Migdal-Eliashberg calculations are commonly performed on…
Recent experiments on certain Fe-based superconductors have hinted at a role for paired electrons in "incipient" bands that are close to, but do not cross the Fermi level. Related theoretical works disagree on whether or not strong-coupling…
Isotope effects in a multiband superconductor with a leading interband pairing channel are investigated. A relatively small electron-phonon contribution into the pair-transfer interaction can cause effects of observed magnitude. A multiband…
We study superconductivity in two-band models where one of the bands does or does not intersect the Fermi level depending on the parameter values. Applying a many-variable variational Monte-Carlo method for a Hubbard model on two-leg ladder…