No abstract

No abstract

The Nd doping effect on the room temperature magnetoresistance in manganites (La 1Àx Nd x ) 0:67 Sr 0:33 MnO 3 was investigated. With increasing Nd doping content in manganites (La 1Àx Nd x ) 0:67 Sr 0:33 MnO 3 the room temperature magnetoresistance ÁR=R 0 decreases for low Nd content x < 0:1, which may be mainly due to the sharp reduction of the room temperature saturation magnetization M S . For x > 0:1, an enhancement of the room temperature magnetoresistance can be obtained. Such enhancement of the room temperature magnetoresistance is correlated with the shift of the Curie temperature to near room temperature and the slow change of the room temperature saturation magnetization M S induced by the appropriate Nd doping. The ÁR=R 0 become small again at large Nd doping contents. The drop of ÁR=R 0 may be attributed to their lower metal-insulator transition temperature T MI far from the room temperature and the smaller M S value at room temperature. Values of the room temperature magnetoresistance ÁR=R 0 for manganites (La 1Àx Nd x ) 0:67 Sr 0:33 MnO 3 depend not only on the Curie temperature T C but also on the metal-insulator transition temperature T MI and the room temperature saturation magnetization M S .