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Epitaxial La_(2/3)Ca_(1/3)MnO_3 thin films were prepared on NdGaO_3 (110) substrates by d.c. magnetron sputtering method. The measurements of magnetoresistance ρ(H) upon magnetic field at different temperatures were carried out in the field range of 0—8 T. It is found that ρ(H) obeys the following relations: when the temperature (T) is higher than the Curie temperature T_C, ρ(H)=1/(α(T)+β(T)H~2); below T_C, ρ(H)=ρ_0(T)+1/(A(T)+B(T)exp(H/c(T)), and ρ(H)=(1/(σ(T)+γ(T)H)) when T is far below T_C. It is suggested that the negative magnetoresistive effect is mainly due to enhancement of the magnetoconductanee.
Epitaxial La_ (2/3) Ca_ (1/3) MnO_3 thin films were prepared on NdGaO_3 (110) substrates by dc magnetron sputtering method. The measurements of magnetoresistance ρ (H) upon magnetic field at different temperatures were carried out in the field range of 0-8 T. It is found that ρ (H) obeys the following relations: when the temperature (T) is higher than the Curie temperature T_C, ρ (H) = 1 / (α (T) + β ) H ~ 2); below T_C, ρ H = ρ_0 T + 1 / A T + B T exp H / c T and ρ H = 1 / (σ (T) + γ (T) H)) when T is far below T_C. It is suggested that the negative magnetoresistive effect is mainly due to enhancement of the magnetoconductanee.