Charge stripe order near the surface of 12-percent doped La_2-xSr_xCuO₄

A collective order of spin and charge degrees of freedom into stripes has been predicted to be a possible ground state of hole-doped CuO2 planes, which are the building blocks of high-temperature superconductors. In fact, stripe-like spin and charge order has been observed in various layered cuprate systems. For the prototypical high-temperature superconductor La2−xSrxCuO4, no charge-stripe signal has been found so far, but several indications for a proximity to their formation. Here we report the observation of a pronounced charge-stripe signal in the near surface region of 12-percent doped La2−xSrxCuO4. We conclude that this compound is sufficiently close to charge stripe formation that small perturbations or reduced dimensionality near the surface can stabilize this order. Our finding of different phases in the bulk and near the surface of La2−xSrxCuO4 should be relevant for the interpretation of data from surface-sensitive probes, which are widely used for La2−xSrxCuO4 and similar systems