Spin waves and large electron-phonon coupling near the metal-insulator transition in hole-doped high-T-c oxides - art. no. 060507

The effects of spin and lattice modulations on the band structure of high-T -c oxides are described, with HgBa2CuO4 as an example. A simple model for b and gaps induced by potential perturbations with long-range Fourier compone nts is applied to the barrel band. The opening of gaps is confirmed in self -consistent band calculations for modulations in elongated supercells, wher e spin waves and phonon coupling compete for equal q vectors. It is argued that the wavelengths of spin-wave modulations, and of the phonon modes with large coupling, depend on the doping. This mechanism supports the idea tha t pseudogaps are caused by stripelike spin modulations in underdoped system s, while superconductivity is attributed to enhanced electron-phonon coupli ng for long-wavelength phonons.