Effect of ruthenium doping on the properties of Pr0.5A0.5MnO3 (A=Ca,Sr)

The effect of ruthenium substitution on Pr0.5A0.5MnO3 (A=Ca, Sr) has been investigated. Pr0.5Ca0.5MnO3 is a charge-ordered antiferromagnetic insulator and 1% Ru4+ doping induces ferromagnetism (TC=150 K) and an insulator–metal transition. Charge ordering is suppressed but not destroyed. Increasing the ruthenium content to 3% completely destroys charge ordering and shifts the TC to 215 K. Pr0.5Sr0.5MnO3 goes from a ferromagnetic metallic state to an antiferromagnetic insulating state. Doping by ruthenium is seen to effect an insulator–metal transition and the antiferromagnetic state is completely destroyed.