Effect of Ga and Ge substitution in the Mn site of rare earth manganates on charge ordering and related properties

The effect of substitution of Ga and Ge in the Mn site on the magnetic and electrical transport properties of three charge-ordered rare-earth manganates, Nd0.5Ca0.5MnO3, Nd0.5Sr0.5MnO3 and Ca0.64Pr0.36MnO3 has been investigated. Substitution by Ga and Ge affects the properties of these charge-ordered manganates differently though they both have the d10 electron configuration. Thus, Ga doping in Nd0.5Ca0.5MnO3 is more effective in destroying the charge ordering than Ge doping, the latter requiring higher concentrations. Substitution of Ga in Nd0.5Sr0.5MnO3 destroys ferromagnetism whereas Ge substitution does not. The charge-ordered antiferromagnetic transition is destroyed by both Ga and Ge substitution and the Ge substituted compositions show itinerant electron behavior while the Ga substituted compositions become insulators. Both Ga and Ge substitution have negligible effect on the charge-ordered state of Ca0.64Pr0.36MnO3.