First time determination of the microscopic structure of a stripe phase: Low temperature NMR in La2NiO4.17 - art. no. 237201

The experimental observations of stripes in superconducting cuprates and in sulating nickelates clearly show the modulation in charge and spin density. However, these have proven to be rather insensitive to the harmonic struct ure and (site or bond) ordering. Using La-139 NMR in La2NiO4+delta with del ta = 0.17, we show that in the 1/3 hole doped nickelate below the freezing temperature the stripes are strongly solitonic and site ordered with Ni3+ i ons carrying S = 1/2 in the domain walls and Ni2+ ions with S = 1 in the do mains.