Metal–insulator–metal transition in Ti substituted antiferromagentic Ru2MnGe Heusler alloy

We report the composition-induced metal–insulator crossover transition in Ti substituted Ru-based metallic full Heusler alloy Ru2MnGe where the both end of materials shows a metallic properties. The samples at the middle composition show the large negative magnetoresistance effect. The experimental results of the resistivity and the magnetization indicate that this metal–insulator transition is induced by the Kondo effect because Ti atoms on antiferromagnetic Ru2MnGe have an important role in appearance of insulator states.

► The ferromagnetic insulators are found in the Ru-based Heusler compounds.
► These materials are the Ti substituted metallic antiferromagnet Ru2MnGe.
► These samples show the ferromagnetism and the large negative MR effect.
► The MR effect was shown below magnetic ordering temperature.
► These facts are interpreted by the magnetic impurity model.