Kinetic energy driven stripe formation and pairing in repulsive electronic systems
We study repulsive Hubbard and t-J type systems on a square lattice (long believed to capture certain quintessential aspects of the high temperature superconductors). These models (alongside the parent compounds of the high temperature superconductors) are antiferromagnetic in the absence of hole doping. As we illustrate, a unifying underlying principle for the dynamics of holes introduced by doping rationalizes the emergence of nonuniform electronic structures- "stripes" and possible pairing tendencies therein. Specifically, our analysis invokes the following (numerically verified) sublattice parity principle: a strong antiferromagnetic background forces injected holes to hop in steps of two such that they always remain on the same sub lattice. When applied to a domain wall in an antiferromagnet, this simple principle naturally gives rise to (bond centered) stripes. We demonstrate that the holes are self-consistently localized on stripes. Extending this picture, we then show that the holes on a stripe favor the formation of pairs on neighboring rungs or sites. Throughout this work much emphasis is placed on the problem of a two leg ladder immersed in a staggered magnetic field. Although we will focus on the square lattice, our considerations may be extended to similar electronic structures appearing in other models on bipartite lattices when these exhibit antiferromagnetic correlations with an underlying sublattice structure.