【摘要】 在La0.67Ca0.33MnO3中用Dy对La进行了部分替代。结果表明,随替代量增加,材料的居里温度和相变温度单调下降,磁电阻比急剧增大。这些变化可以用稀土离子平均直径的减小和自旋团簇模型来解释。掺Dy使材料中形成大量无序自旋团簇,外加磁场使自旋团簇取向一致,从而增加了电子在团簇之间跳跃时的迁移率,产生了磁场所致的庞磁电阻效应。更多还原

【Abstract】 The Dy substituting effects for La in La_0.67Ca_0.33MnO₃ was investigated. With increasing substituting amount of Dy, the Curie temperature T_C, the phase transition temperature T_P for the samples decrease monotonically, while the corresponding CMR effect increases dramatically. These changes can be explained in terms of the decrease in average diameter of rare-earth ions and the model of spin clusters. The disordered spin clusters are induced in the samples due to the Dy doping. The magnetic field aligns the spin clusters and increases the mobility of the electron’s hopping between spin clusters. This causes the magnetoresistance to change significantly.更多还原