[en] Three transition temperatures have been found in the M(T) curve in a lightly doped La₂CuO_4+δ sample. The high temperature transition around 239 K corresponds to the Neel transition. The low temperature transition appearing at 35 K is due to the superconducting transition. A weak but apparent transition appears at a medium temperature of about 110 K, which has been clearly observed in previous results, but has attracted no attention. Based on a theoretical model of phase separation, we argue that this weak transition originates from the condensation of ferromagnetic clusters induced by holes within the antiferromagnetic background