The magnetic ordering in the Pr

We investigated the magnetic properties of the Pr$_{0.5-x}$NdxSr0.5MnO3 (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) system. Since the two end samples Pr0.5Sr0.5MnO3 and Nd0.5Sr0.5MnO3 are A-type and CE-type AFM at low temperatures, respectively, due to their different orbital ordering $d_{(x^{2}-y^{2})}$ and $d_{(3x^{2}-r^{2})}$/$d_{(3y^{2}-r^{2})}$, the magnetic structure of Pr$_{0.5- x}$NdxSr0.5MnO3 is expected to be a mixture of A- and CE-type AFM. Our experiment results show that TC remains almost constant, while TN decreases dramatically as Pr3+ ions are replaced by Nd3+ ions. We suggest that this originates from the orbital ordering instability of the different magnetic structure type rather than from the ionic radius at the A-site