Nonadiabatic polaronic superconductivity in MgB2 and cuprates

Nonadiabatic polaronic superconductivity in MgB2 and cuprates

Superconductivity in Fe and As based compounds: A bridge between MgB2 and cuprates

By interpreting various experimental data for the new high temperature FeAs type superconductors in terms of lattice mediated multigap superconductivity, it is shown that these systems strongly resemble MgB2, however, with the distinction that local polaronic lattice effects exist. This fact establishes a connection to cuprate high temperature superconductors where polaron formation is essentia...

Oxygen Isotope Effects on Tc Related to Polaronic Superconductivity in Underdoped Cuprates

The planar oxygen isotope effect on Tc observed in copper oxide superconductors is remarkable in that it increases from near nil at optimal doping to a value twice that derived from BCS theory in the underdoped region. This behavior is quantitatively followed by a formula proposed by Kresin and Wolf in 1994 for polarons along the c-axis. Herein it is revisited in a more transparent way, and it ...

Superconductivity in the cuprates

We evaluate numerically several superconducting correlation functions in a generalized t − J model derived for hole-doped CuO2 planes. The model includes a three-site term t similar to that obtained in the large U limit of the Hubbard model but of opposite sign for realistic O-O hopping. For realistic parameters we obtain strong evidence of superconductivity of predominantly dx2−y2 character. T...

d - wave nonadiabatic superconductivity

The inclusion of nonadiabatic corrections to the electron-phonon interaction leads to a strong momentum dependence in the generalized Eliashberg equations beyond Migdal's limit. For a s-wave symmetry of the order parameter, this induced momentum dependence leads to an enhancement of Tc when small momentum transfer is dominant. Here we study how the d-wave symmetry affects the above behavior. We...