Unexpected effect of Ru-substitution in lightly doped manganites
  In this Communication we report about the unexpected effect of ruthenium doping in sodium ligthly-doped manganites. This effect seems to be in contrast with the usual model applied to describe the effect of this magnetic ion into the manganite structure. We propose a possible compensation mechanism which seems also able to describe other peculiar features encountered in these materials. 
Lorenzo Malavasi, M. Cristina Mozzati, Cristina Tealdi, M. Rosa   Pascarelli, Carlo B. Azzoni and Giorgio Flor