Effect of rare earth ion substitution on the magnetic and transport properties of Pr $_{\mathsf{0.7}}$RE $_\mathsf{0.04}$Sr $_\mathsf{0.26}$MnO$_\mathsf{3}$ (RE = Er$^\mathsf{3 + }$, Tb$^\mathsf{3 + }$ and Ho$^\mathsf{3 + }$)

Abstract.

The effect of rare earth ion (RE = Er^{3 +} , Tb^{3 +} , Ho^{3 +} ) substitution in Pr_0.74Sr_0.26MnO₃ (PSMO(0.26)) on the magnetic and transport properties is reported. It is found that even for a small concentration of substitution of Pr^{3 +} ions by Er^{3 +} , Tb^{3 +} , or Ho^{3 +} ions there is a significant change in the transport and magnetic properties compared to the parent compound Pr_0.74Sr_0.26MnO₃. The observed changes are attributed to the increase in the average A-site disorder upon substituting smaller ions (ionic radius of Er^{3 +} = 1.062 Å, Ho^{3 +} = 1.072 Å, Tb^{3 +} = 1.095 Å) in place of bigger Pr^{3 +} ion (ionic radius = 1.179 Å). The Ho^{3 +} substituted sample was found to behave anomalously when compared to the other two rare earth ion-substituted (Tb^{3 +} and Er^{3 +} ) samples. Such anomalous behaviour could most likely be caused by the magnetic coupling of the Ho and Mn ions.