【作者】 卫芬芬； 熊曹水； 熊永红；

【Author】 WEI Fen-fen~1,XIONG Cao-shui~2,XIONG Yong-hong~2 (1.Key Laboratory of Ecophysics and Department of Physics,Normal College,Shihezi University, Shihezi 832003,China; 2.Physics Department,Huazhong University of Science and Technology,Wuhan 430074,China)

【机构】 石河子大学师范学院物理系生态物理重点实验室； 华中科技大学物理学院；

【摘要】 通过固相反应法制备La_0.7Ca_0.2Sr_0.1MnO₃/xCoFe₂O₄（LCSMO/xCFO）复合样品,用X射线衍射（XRD）、扫描电子显微镜（SEM）、振动样品磁强计（VSM）以及直流四探针法测试,对复合材料的结构及磁电性能进行了研究。结果表明,随着CFO的掺杂,复合材料的结构没有发生变化,CFO颗粒主要分布在LCSMO颗粒的晶界处,但在0～20%的掺杂范围内,电阻率大幅度增加,出现了双峰;而居里温度（T_C）没有发生变化,在T<T_C,磁化强度逐渐减小,在T>T_C磁化强度又逐渐增大。复合样品在温度远小于绝缘体—金属转变温度（T_P）的低场下（约0.239kA/m）出现大的磁电阻效应,这是一种非本征磁电阻效应,起因于分布在LCSMO的颗粒晶界处CFO引起传导电子受到的自旋相关散射。更多还原

【Abstract】 La_0.7Ca_0.2Sr_0.1MnO₃/xCoFe₂O₄（LCSMO/xCFO） samples were prepared by solid state reaction method. X-ray diffraction（XRD）,scanning electronic microscopy（SEM）,vibrating sample magnetometer（VSM） and Dc four probed method were used to investigate the structure and properties.The results show that that CFO mainly segregated at the boundaries of LCSMO grains,which did not change the structure of LCSMO.In the doping range of 0-0.35,the resistivity rises remarkably,furthermore,the resistivity versus appears double peaks with increasing CFO doping amount.While T_C is unchanged,T_C is a dividing point,the magnetization changed with the increase of CFO.The composites present a sizable magnetoresistance at much lower temperature than T_p when applied a small field（about 0.239kA/m）,this is an extrinsic MR effect,and the magnetic scattering of polarized charge carriers may be responsible for enhanced extrinsic MR of the composites.更多还原