Transport Properties in La_(0.7-x)Dy_xSr_(0.3)MnO_3 System

The influence of Dy doping at La-site on transport properties of La0.7-xDyxSro.3MnO3 (x=0.00, 0.10, 0.15, 0.20, 0.30, 0.40, 0.50, 0.60, and 0.70) was studied. The experimental results indicate that with increasing Dy doping, the system undergoes a transition from long range ferromagnetic order to the cluster-spin glass state and further to antiferromagnetic order. The transport properties exhibit abnormal behaviour at high doping condition. For x=0.50, a transition from metal to insulator occurs after the occurrence of insulator-metal transition near Tc, which seldom occurs in ABO3 structure. The samples of x=0.60 and 0.70, exhibit insulator behavior far above Tc.