Polaronic Mechanism of Superconductivity in Cuprates

Nonadiabatic polaronic superconductivity in MgB2 and cuprates

Spin-Fluctuation Mechanism of Superconductivity in Cuprates

Normal and superconducting state spectral properties of cuprates are theoretically described within the extended t-J model. The method is based on the equations of motion for projected fermionic operators and the mode-coupling approximation for the self-energy matrix. The dynamical spin susceptibility at various doping is considered as an input, extracted from experiments. The analysis shows th...

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 ...

Fundamental constraints for the mechanism of superconductivity in cuprates

Considerable progress has been made over the last decade in understanding the phenomenological properties of the cuprate high-Tc superconductors and in producing well characterized high quality materials. Nevertheless, the pairing mechanism itself remains controversial. We establish a criterion to test theories for layered superconductors relying on a substantial interlayer contribution. The cr...

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...