Enhancement of low-field magnetoresistance in the composite system of La_(0.6)Dy_(0.1)Sr_(0.3)MnO_3 with Ag

The samples of La0.6Dy0.1Sr0.3MnO3/Agx(x=0,0.04) were prepared by solid-state reaction method.The magnetic property,transport behavior,transport mechanism and magnetoresistance effect of the samples were studied through the measurements of XRD patterns,M-T curves,and ρ-T curves.The results indicate that: the Ag phase appears when the amount of introduced Ag is small,and it mainly separates to the grain boundary of the mother body as metallic state,then the system forms a two-phase composite.The peak magnetoresistance of the sample covered with Ag strengthens apparently and reaches 9.1% at 296 K and in the magnetic field of 0.2 T,and it is over four times as large as 2.2% of La0.6Dy0.1Sr0.3MnO3.It is attributed not only to the improvement of the grain boundary structure of the mother body but also to the decrease of material resistivity.The magnetoresistance of the sample covered with Ag is above 20% in the temperature range of 45-130 K,so the extension of the temperature range of magnetoresistance is realized.