Effect of rare earth ion substitution on the magnetic and transport properties of Pr

The effect of rare earth ion (RE = Er3+, Tb3+, Ho3+) substitution in Pr0.74Sr0.26MnO3 (PSMO(0.26)) on the magnetic and transport properties is reported. It is found that even for a small concentration of substitution of Pr3+ ions by Er3+, Tb3+, or Ho3+ ions there is a significant change in the transport and magnetic properties compared to the parent compound Pr0.74Sr0.26MnO3. The observed changes are attributed to the increase in the average A-site disorder upon substituting smaller ions (ionic radius of Er3+ = 1.062 Å, Ho3+ = 1.072 Å, Tb3+ = 1.095 Å) in place of bigger Pr3+ ion (ionic radius = 1.179 Å). The Ho3+ substituted sample was found to behave anomalously when compared to the other two rare earth ion-substituted (Tb3+ and Er3+ samples. Such anomalous behaviour could most likely be caused by the magnetic coupling of the Ho and Mn ions