Study of charge and spin order in La2NiO4+delta using La-139-NMR

La-139-NMR and magnetic susceptibility measurements as functions of temperature (T) were performed in a single crystal of La2NiO4+delta. The crystal was checked by x-rays and microprobe analyses for homogeneity. Thermogravimetric analysis yields delta = 0.17. Linewidth and normalized NMR intensity measurements of the central transition between 350 and 40 K reveal unambiguous features for several T-values. The intensity increases as T is decreased through 310 K, displaying strong T-dependence down to 230 K, where it saturates. The full width at half maximum of the main spectral line plateaus between 270 and 230 K and grows by a factor of about 10 between 230 and 40 K. For T > 200 K, the data are consistent with the interpretation of current neutron-scattering experiments by Tranquada et al. However, no indication of spin order is observed until below similar to 50 K.