Do shifting Bragg peaks of cuprate stripes reveal fractionally charged kinks?

Abstract

The stripe phases found in correlated oxides can be viewed as an ordering of the solitons associated with doping the Mott-insulating state. Inspired by the recent observation that the stripes tilt away from the main axis of the crystal lattice in the regime x = 1/8, we propose that a new type of stripe phase is realized in the large doping regime. This new phase should be viewed as a doped version of the microscopically insulating x = 1/8 stripes. The topological excitations associated with the extra doping are fractionally charged kinks along the stripes whose motions make the stripe fluctuate. We argue that the directional degree of freedom of the kinks might order, causing the stripe phase to tilt. Quantitative predictions follow for the doping dependence of the tilt angle, which in turn can be used to determine the fundamental charge quantum associated with the stripe phase.