X-ray scattering study of charge scattering associated with stripe order in La2NiO4

In this paper we report the first observation of stripe correlations of holes in hole-doped La2NiO4 by X-ray diffraction. The experiment was performed in Laue geometry at the hard X-ray beamline BW5 at HASYLAB on a crystal of La1.77Sr0.22NiO4 previously studied by neutron diffraction. Temperature dependences of the intensities and wave vectors of the charge-density-modulation peaks were characterized and found to be in good agreement with the neutron scattering results. Interestingly, weak, temperature-dependent scattering was also observed at positions consistent with nonresonant X-ray magnetic scattering from the spin correlations; however, a definitive determination of its origin remains lacking.