Magnetic transitions in the perovskites Pr1-xSrxCoO3

The magnetic and electrical properties of Pr1-xSrxCoO3 cobaltites with 0.3 ≤ x ≤ 0.5 were studied in the temperature range 5 K ≤T ≤ 1000 K and field, up to 7 T. These cobaltites exhibit two phase transitions: a paramagnetic-ferromagnetic phase transition below about 240 K and a second one below 110 K. The temperature dependences of the magnetizations of Sr doped samples show differences in the FC and ZFC data. The samples were also investigated by μSR experiments in zero field (ZF) and weak transverse field (wTF). The μSR data clearly indicate the existence of the two transitions. The samples show small negative magnetoresistances that are controlled by grain-boundary effects. The results suggest a change in the nature of magnetic coupling between Co ions at low temperature magnetic transition.