Structural , electrical and magnetic properties of RE 1 / 3 Sr 2 / 3 FeO 3 compounds ( RE = La , Pr , Nd , Eu and Gd )

We report results of structural, magnetic and electrical measurements performed on the perovskite RE1/3Sr2/3FeO3 compounds (RE= rare earth). Samples with light RE (La, Pr or Nd) show a metal-insulator-like transition coupled to an antiferromagnetic ordering upon cooling. This transition is believed to be brought about by a charge ordering of Fe and Fe ions in the low temperature phase accompanied by the concomitant structural transition. The replacing of light RE by heavy ones (Gd or Eu) gives rise to high-resistivity compounds with no metal-insulator transition. However, the magnetic transition remains at low temperatures. A previous Mössbauer study reports similar behaviour for RE=Eu compound. This suggests that variations in Mössbauer spectra may be of a magnetic origin in light RE compounds and not coming from a full charge disproportionation of Fe as deduced previously.