Investigation of charge order manganites Nd0.5Ca0.5Mn0.95A0.025B0.025O3 (A=Ti/Ru; B=Cr/Ga)

The magnetism and electronic transport properties in the Nd0.5Ca0.5Mn0.95A0.025B0.025O3 manganites have been studied. The doped sample provides a good system to detect the impurity effect in charge ordering materials due to a fixed ratio of Mn3+:Mn4+=1. We find that the induced ferromagnetism stems from the exchange couple between the magnetic impurity and Mn element. The local charge ordering phase forms an antiferromagnetic coupling whereas its intensity weakens with the decrease of temperature. In the high temperature region, the electronic transport occurs in the variable-range hopping manner.