Transport mechanism in polycrystalline La0.825Sr0.175Mn1-xCuxO3

The transport mechanism of polycrystalline samples La0.825Sr0.175Mn1-xCuxO3 (0 less than or equal to x less than or equal to 0.20) and the effects of Cu doping have been investigated. It can be concluded that the existence of Cu induces the superexchange interaction and weakens the long range ferrom agnetic order in the samples. The transport mechanism in the metallic regim e is attributed to the magnon-carrier scattering and the transport mechanis m in the insulating regime transits from polaron transport to variable-rang e hopping with the adding of Cu. The effect of the surface phase is also ob served in the samples.