Reappearance of Antiferromagnetic Order in $Nd_{0.9}Ca_{0.1}BaCo_{2}O_{5+δ}$ for δ > 0.51

The absence of the antiferromagnetic order in $Nd_{0.9}Ca_{0.1}BaCo_2O_{5.5}$ has been found to remain unchanged by applying a hydrostatic pressure of 10 kbar. In magnetic studies of polycrystalline $Nd_{0.9}Ca_{0.1}BaCo_2O_{5+δ}$ (δ=0.07-0.69), we have found a reappearance of the antiferromagnetic phase, caused by an increase in oxygen index δ above 0.51 related to extra oxygen ions addition into the $NdO_{δ}$ plane. For the samples with δ=0.555 and 0.59, a coexistence of well developed antiferromagnetic phase with ferrimagnetic one is evidenced.