La0.7Ca0.3MnO3多晶材料制备及其电磁特性

以化学溶液分解法制备La0.7Ca0.3MnO3粉体,常压烧结制备多晶块体样品。对La0.7Ca0.3MnO3样品的磁矩、磁致电阻效应（CMR）和电脉冲诱导电阻转变效应（EPIR）进行了研究。磁矩零场冷和场冷试验结果发现,居里温度以下,零场冷和场冷条件下磁矩具有较大差别。这说明材料中缺少真正的长程磁有序。La0.7Ca0.3MnO3多晶具有磁致电阻效应,在9 T磁场作用下,磁致电阻变化大约为70%。在80 V,20 ns电脉冲作用下,材料具有电脉冲诱导电阻转变效应。从理论上对磁致电阻效应与电脉冲诱导电阻转变效应的机理进行了分析。

The Synthesis and Electromagnetic Properties of La0.7Ca0.3MnO3

Single phase La0.7Ca0.3MnO3（LCMO） powder was synthesized by a chemical solution deposition（CSD） method and the polycrystalline sample was prepared by pressureless sintering method.The magnetic moment properties,colossal magnetoresistance（CMR） effect and electric-pulse-induced switching of electrical resistance effect were studied.The absence of true long range order is apparent from the large difference between zero field cooled and field cooled conditions below Tc,which are the typical characteristics of the possible existence of a spin-glass or antiferromagnetic phase.The CMR effect and EPIR effect were found in La0.7Ca0.3MnO3.Because La0.7Ca0.3MnO3 polycrystalline bulk sample is much thicker than thin film,the threshold value of electric pulse employed in the present experiment is 80 V.The theory of CMR effect and EPIR effect are discussed.