Magnetoresistance Effects for the Inhomogeneous Perovskite System of Ag Doped La(0.833)Na(0.167)MnO3

摘要

The transport properties of the inhomogeneous system (1/4)Ag2O-La(0.833)Na(0.167)MnO3 (LNMO/Ag) have been systematically studied. X-ray diffraction patterns show that the LNMO/Ag sample is the twophase composite and consists of a magnetic La(0.833) Na(0.137)MnO3 (LNMO) perovskite phase and a nonmagnetic Ag metal phase. The resistivity of the sample decreases dramatically with Ag added into the pure perovskite LNMO manganites. For the LNMO/Ag sample, the Curie temperature TC is 331 ± 2 K and slightly higher than that of the LNMO sample (323 ± 2 K). Due to the dope of Ag metal, the room temperature magnetoresistance effect is enhanced significantly (from 7% for the pure LNMO manganites to 23% for the LNMO/Ag sample under a relative lower field of 0.5 T and from 37.5% for the LNMO sample to 41% for the LNMO/Ag sample under a high field of 6 T at the temperature of 330 K. In the low temperature regime, the magnetoresistance ratio of the LNMO/Ag sample is smaller than that of the LNMO sample, which is contrary to the magnetoresistance effect in high temperature. The effects are discussed qualitatively by use of a model which is based on the relative change among the intrinsic magnetoresistance effect and the extrinsic magnetoresistance effect.