  We studied the nano-scale structure of the short-range incommensurate
magnetic order in La1.5Sr0.5CoO4 by elastic neutron scattering. We find that
magnetic diffuse scattering is isotropic in the a-b plane, in contrast with the
naive expectation based on the popular stripe model. Indeed, charge segregation
into lines favoring certain lattice direction(s) would facilitate linear
stacking faults in an otherwise robust antiferromagnetism of un-doped material,
leading to anisotropic disorder, with a characteristic symmetry pattern present
in the neutron scattering data.
