  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
$T_{\rm c}=42$ 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 $\hbar \omega = 0.3-10$ 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.
