Mesoscopic phase separation inLa2CuO4.02:A139LaNQR study

Abstract

In crystals of ${\mathrm{La}}_{2}{\mathrm{CuO}}_{4.02}$ oxygen diffusion can be limited to such small length scales that the resulting phase separation is invisible for neutrons. Decomposition of the ${}^{139}\mathrm{La}$ nuclear quadrupole resonance spectra shows the existence of three different regions, of which one orders antiferromagnetically below 17 K concomitantly with the onset of a weak superconductivity in the crystal. These regions are compared to the macroscopic phases seen previously in the title compound and the cluster-glass and striped phases reported for the underdoped Sr-doped cuprates.