arXiv subjects

O. V. Danylenko

Publications and source records attributed to O. V. Danylenko.

4 recordsLinked to original sources

arXiv2000

Nonadiabatic Contribution to the Quasiparticle Self-Energy in Systems with Strong Electron-Phonon Interaction

We investigate effects of a nonadiabatic electron-phonon(boson) interaction on the quasiparticle self-energy in the lowest order in the coupling constant. Existing approaches either overestimate, or underestimate these effects because of different approximations for momentum and frequency dependences of the vertex corrections. The connection between the nonadiabaticity and a possible instability of the interacting Fermi system is discussed as well.

cond-mat.supr-con↗

arXiv1998

Forward Electron-Phonon Scattering in Normal and Superconducting States

The sharp forward electron-phonon $(FEP)$ and impurity $(FIS)$ scattering change the normal and superconducting properties significantly. The pseudo-gap like features are present in the density of states for $ω<Ω$, where $Ω$ is the phonon frequency. The superconducting critical temperature $T_c$, due to the $FEP$ pairing, is linear with respect to the electron-phonon coupling constant. The $FIS$ impurities are pair weakening for $s-$ and $d-wave$ pairing.

cond-mat.supr-con↗

arXiv1997

Normal and superconducting state in the presence of forward electron-phonon and impurity scattering

Impurities with the pronounced forward scattering (FS impurities) change analytical properties of the quasiparticle Green's function substantially compared to the isotropic scattering. By assuming that the superconducting pairing is due to the forward E-P scattering (FEP pairing) it is shown that the critical temperature of clean systems T_{c0} depends linearly on the E-P coupling constant λand the isotope effect αis small. The FS impurities make α=1/2 in the dirty limit and affect in the same way the s- and d-wave FEP pairing. The FS impurities are pair-weakening in both pairing channels. The usual isotropic impurity scattering is pair-weakening for the s-wave and pair-breaking for the d-wave FEP pairing.

cond-mat.supr-con↗

arXiv1997

The Ward identity and nonadiabatic corrections to the quasiparticle self-energy

In some newly discovered materials the ratio of phonon to electron energies is no longer small. We have investigated the basement of the recently proposed gauge-invariant self-consistent method and found conditions of its applicability.

cond-mat.supr-con↗