Enhancement of room-temperature magnetoresistance in La_(0.5)Sm_(0.2)Sr_(0.3)MnO_3/(Ag_2O)_(x/2)  

作　　者：PENG Zhensheng WANG Guiying TANG Yonggang LIU Peng NIU Xiaofei 

机构地区：[1]Anhui Key Laboratory. of Spintronics and Nano-materials Research, Suzhou College, Suzhou 234000, China [2]Structure Research Laboratory, University of Science and Technology of China, Hefei 230026, China

出　　处：《Rare Metals》2010年第1期45-49,共5页稀有金属（英文版）

基　　金：supported by the Key Program of the National Natural Science Foundation of China (No. 19934003);the Grand Program of Natural Science Research of Anhui Education Department (No. ZD2007003-1);the Natural Science Research Program of Universities and Colleges of Anhui Province, China (Nos. KJ2008A19ZC, KJ2009B281Z, and KJ2009A053Z)

摘　　要：La0.5Sm0.2Sr0.3MnO3/（Ag2O）x/2 （x = 0.00, 0.04, 0.08, 0.25, 0.30） samples were prepared by the solid-state reaction method, and their transport behaviors, transport mechanism, and magnetoresistance effect were studied through the measurement and fitting of p-T curves. The results show that the element Ag takes part in reaction when the doping amount is small. Ag is mainly distributed at the grain boundary of the host material and is in metallic state when the doping amount is relatively large; then the system becomes a two-phase composite. A small amount of Ag doping can apparently increase grain-boundary magnetoresistance induced by the spin-dependent scattering. The resistivity of the sample doped with 30 mol% Ag is one order of magnitude smaller than that of low-doped samples, and its magnetoresistance in the magnetic field of 0.5 T and at 300 K is strengthened apparently reaching 9.4%, which is connected not only with the improvement of the grain-boundary structure of the host material but also with the decrease of material resistivity.La0.5Sm0.2Sr0.3MnO3/（Ag2O）x/2 （x = 0.00, 0.04, 0.08, 0.25, 0.30） samples were prepared by the solid-state reaction method, and their transport behaviors, transport mechanism, and magnetoresistance effect were studied through the measurement and fitting of p-T curves. The results show that the element Ag takes part in reaction when the doping amount is small. Ag is mainly distributed at the grain boundary of the host material and is in metallic state when the doping amount is relatively large; then the system becomes a two-phase composite. A small amount of Ag doping can apparently increase grain-boundary magnetoresistance induced by the spin-dependent scattering. The resistivity of the sample doped with 30 mol% Ag is one order of magnitude smaller than that of low-doped samples, and its magnetoresistance in the magnetic field of 0.5 T and at 300 K is strengthened apparently reaching 9.4%, which is connected not only with the improvement of the grain-boundary structure of the host material but also with the decrease of material resistivity.

关 键 词：low-field magnetoresistance room-temperature magnetoresistance grain-boundary magnetoresistance two-phase composite perovskite manganite 

分 类 号：O484.43[理学—固体物理] O614.122[理学—物理]