【作者】 徐美华； 胡秀坤； 张世远；

【Author】 Xu Meihua, Hu Xiukun, Zhang Shiyuan(National Laboratory of Solid State Microstructure , Department of Physics , Nanjing University , Nanjing 210093, China ; Department of Applied Physics , Nanjing University of Technology, Nanjing 210009, China)

【机构】 南京大学固体微结构重点实验室 南京大学物理系；

【摘要】 采用固相反应法制备了一系列(La1-xSmx)2/3Sr1/3MnO3(0≤x≤0．7)大块多晶样品。测量了它们的结构、磁电阻、磁致伸缩等磁电性质。实验结果表明随着Sm含量x值的增大,A位的平均离子半径减小,样品的居里温度降低,零场电阻率在温度Tp处的峰值增大,相应的磁电阻增大。对x=0．6和0．7样品的磁致伸缩测量结果表明,样品的各向异性磁致伸缩λt几乎为零,而体磁敛伸缩ω值均为负值,表明样品体积在温度下降到铁磁居里温度以下时是收缩的,而且在磁场高达7T时也未达到饱和。对于x=0．6样品,在210 K附近,7 T时最大的ω值为-550×10-6。这是因为样品中由于用离子半径较小的Sm3+部分取代位于A位的离子半径较大的La3+时出现了相分离。更多还原

【Abstract】 A series of bulk polycrystalline (La1-x Sm2)2/3Sr1/3MnO3(x = 0.0, 0.2, 0.4, 0.6, 0.7) samples were prepared by solid-phase reaction meth- od. Their structures, magnetoresistances and magnetostrictions were studied. The experimental results indicate that with increasing Sm content x, the average ionic radius of the A site < rA > and Curie temperature of the samples decrease, the maximum of the zero-field resistivity at TP and corresponding magnetore-sistance increase. The magnetostriction measurement shows that the anisotropic magnetostriction coefficients λt nearly are zero, while the volume magnetostriction coefficients are negative for x - 0.6 and 0.7 samples, which imply that the volumes of the samples is cont- racted when temperature decreases through the Curie temperature, and there are not saturated even under 7 T strong magnetic field. For the x = 0.6 sample, the maximum ω of - 550×10-6 at about 210 K and 7 T was observed. These experimental results can be interpreted by the viewpoint of phase separation owing to the substitution of Sm3+ with smaller ionic radius for La3+ with larger ionic radius in the samples.更多还原