Spin twists, domain walls, and the cluster spin-glass phase of weakly doped cuprates

We examine the role of spin twists in the formation of domain walls, often called stripes, by focusing on the spin textures found in the cluster spin glass phases of La2-xSrxCuO4 and Y1-xCaxBa2Cu3O6. To this end, we derive improved analytic expressions for the spin distortions produced by a frustrating-bond, both near the core region of the bond and in the far field, and then derive an improved expression for interaction energies between such beads. We critique our analytical theory by comparison to numerical solutions of tills problem and find excellent agreement. By looking at collections of small numbers of such bonds localized in some region of a lattice, we demonstrate the stability of small "clusters" of spins, each cluster having its own orientation of its antiferromagnetic order parameter. Then, we display a domain wall corresponding to spin twists between clusters of locally ordered spins showing how spin twists can serve as a mechanism for stripe formation. Since the charges are localized in this model, we emphasize that these domain walls are produced in a situation for which no kinetic energy is present in the problem.