Excess oxygen in La_{2-x}Sr_xCoO_4

Abstract

The amount of non-stoichiometric oxygen in La_{2-x}Sr_xCoO_{4+y} is calculated from Sr doping, x, and the measured stripe incommensurability 2delta for x = 1/4 and x = 1/3 based on a linear or square-root dependence of delta(x, y). The results favor the square-root dependence and indicate that the range of excess oxygen extends to x < 0.4 instead of to x < 0.3 as previously thought, coinciding with the low-temperature orthorhombic (LTO) phase.