Influence of heavy-doping with Dy on the magnetic and electrical properties in La0.7Sr0.3MnO3

Abstract

The M_T curves, M_H curves, ρＴ curves and MR_T curves of La0.7-xDyxSr0.3MnO3 (x=000，030，040，050，060 and 070) are studied. Experimental results indicate that with increasing do ping concentration of Dy, the system changes from long_range ferromagnetic order to cluster_spin glass state, then to antiferromagnetic state and to subferromag netic state. For x=03, there appears a peak on the M_T curve near T N,however, it disappears at x=04. For x=05, and zero field cooli ng(ZFC) the curve shows a valley, and then a peak at TN; after the 001 T field cooling process, the initial value of M is negative at low temperatur es. For x=060 and 070, their ZFC and FC M_T curves are both similar to the ZFC one of x=050, and the transport properties at heavy doping beco me abnormal under a magnetic background. The peculiar phenomena shown above can be interpreted in terms of the Nel's double_lattice model combined with the re sultsof M_H hysteresis at the characteristic temperatures.