Nature of the magnetic stripes in fully oxygenated La${}_2$CuO${}_{4+y}$

Abstract

We present triple-axis neutron scattering studies of static and dynamic magnetic stripes in an optimally oxygen-doped cuprate superconductor, La${}_2$CuO${}_{4+y}$, which exhibits a clean superconducting transition at $T_{\mathrm{c}}=42$ K. Polarization analysis reveals that the magnetic stripe structure is equally represented along both of the tetragonal crystal axes and that the fluctuating stripes display significant weight for in-plane as well as out-of-plane spin components. Both static magnetic order as well as low-energy fluctuations are fully developed in zero applied magnetic field and the low-energy spin fluctuations at $\hslash \ddot{I}‰=0.3-10$ meV intensify upon cooling. We interpret this as an indication that superconductivity and low-energy spin fluctuations co-exist microscopically in spatial regions which are separated from domains with static magnetic order.

16 pages, 6 figures