The ferromagnetic transition temperatures have been measured on two bathes of perovskite manganese oxides such as ( La1-xRx )2/3, Ca1/3 Mn03 ( R = Ce, Pr, Nd, etc.) and Laj/j ( Ca1-y Cdy ) 1/3 MnO3. It is found that t...The ferromagnetic transition temperatures have been measured on two bathes of perovskite manganese oxides such as ( La1-xRx )2/3, Ca1/3 Mn03 ( R = Ce, Pr, Nd, etc.) and Laj/j ( Ca1-y Cdy ) 1/3 MnO3. It is found that the (La1-xRx)2/3Ca1/3MnO3 samples have obviously different Curie temperature Tc although their ( rA) (the average A-site cation radius) are almost identical, and the Tc in the system of (La1-xRx)2/3Ca1/3MnO3 compounds increases with increasing y although ( rA) decreases slightly - It is suggested that the Curie temperature should be influenced by the average local A-site magnetic moment in the ferromagnetic perovskite manganite system.展开更多
Epitaxial La2/3Ca1/3 MnO3 thin films were prepared on NdGaO3(110) substrates by d. c. magnetron sputtering method. The measurements of magnetoresistance ρ(H) upon magnetic field at different temperatures were carried...Epitaxial La2/3Ca1/3 MnO3 thin films were prepared on NdGaO3(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 p(H) obeys the following relations: when the temperature(T) is higher than the Curie temperature Tc, ρ ( H ) =1/α(T)+β(T)H2; below Tc, ρ ( H ) = ρ0 ( T ) 1/A(T)+B(T)exp(H/C(Y)),and ρ(H) =1/κa(T)+γ(T)H when T is far below TC. It is Suggested that the negative magnetoresistive effect is mainly due to enhancement of the magnetoconductance.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No. 19504012)the Chinese Academy of Sciences.
文摘The ferromagnetic transition temperatures have been measured on two bathes of perovskite manganese oxides such as ( La1-xRx )2/3, Ca1/3 Mn03 ( R = Ce, Pr, Nd, etc.) and Laj/j ( Ca1-y Cdy ) 1/3 MnO3. It is found that the (La1-xRx)2/3Ca1/3MnO3 samples have obviously different Curie temperature Tc although their ( rA) (the average A-site cation radius) are almost identical, and the Tc in the system of (La1-xRx)2/3Ca1/3MnO3 compounds increases with increasing y although ( rA) decreases slightly - It is suggested that the Curie temperature should be influenced by the average local A-site magnetic moment in the ferromagnetic perovskite manganite system.
基金Project supported by the National Natural Science Foundation of China (Grant No. 19504012) the Chinese Academy of Sciences
文摘Epitaxial La2/3Ca1/3 MnO3 thin films were prepared on NdGaO3(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 p(H) obeys the following relations: when the temperature(T) is higher than the Curie temperature Tc, ρ ( H ) =1/α(T)+β(T)H2; below Tc, ρ ( H ) = ρ0 ( T ) 1/A(T)+B(T)exp(H/C(Y)),and ρ(H) =1/κa(T)+γ(T)H when T is far below TC. It is Suggested that the negative magnetoresistive effect is mainly due to enhancement of the magnetoconductance.
