Stripes, Carriers, Pseudogap, and Superconductivity in the Cuprates

The electronic structure of the high-T_c cuprates is studied on the basis of both "large-U" and "small-U" orbitals. A striped structure is obtained, and three types of carriers: polaron-like "stripons" carrying charge, "quasielectrons'' carrying charge and spin, and "svivons" carrying spin and lattice distortion. Anomalous properties of the cuprates and specifically their transport properties are derived. Pairing is found to result from transitions between pair states of quasielectrons and stripons through the exchange of svivons. The pairing results in superconductivity when the stripons conduction is coherent, and in a pseudogap phase when it is not.