Disorder-induced static antiferromagnetism in cuprate superconductors.

Using model calculations of a disordered d-wave superconductor with on-site Hubbard repulsion, we show how dopant disorder can stabilize novel states with antiferromagnetic order. We find that the critical strength of correlations or impurity potential necessary to create an ordered magnetic state in the presence of finite disorder is reduced compared to that required to create a single isolated magnetic droplet. This may explain why, in cuprates such as La2-xSrxCuO4, low-energy probes have identified a static magnetic component which persists well into the superconducting state, whereas, in cleaner systems such as YBa(2)Cu(3)O(6+delta), it is absent or minimal.