The enhanced interface effect induced by thermal pressure in Nd0.7Sr0.3MnO y ceramics

Polycrystalline ceramics Nd0.7Sr0.3MnO y prepared by solid-state reaction were treated under high pressure of 9 GPa and temperature of 1000 K. The electrical transport behaviour of samples were investigated by a variable temperature system and a peculiar transport character was found at low temperature of 120 K, the I–V showed an obvious step-shape behaviour with the increase in the measurement voltages; at much lower temperature of 12.3 K, the I–V curves exhibited a notable symmetric hysteresis at a critical voltage of 4.5 V, although a linear I–V behaviour at 293 K. On the other hand, the R–T measurement revealed that the resistivity peak (resistivity at T M I ) disappeared gradually and is replaced by a resistivity platform with the increase in the load currents, surprisingly, the resistivity platform broadened with continuous increase in the load currents but weakened when an external magnetic field was applied. All of these phenomena were not observed for the un-treated sample. The particle attenuated and the enhanced interface effect which resulted from the violent thermal-pressure treatment was responsible for the unique electromagnetic transport.