La_(1-x)Ca_xMnO_3中Ca含量对电子结构的影响

The influence of Ca content on electronic structure of La_(1-x)Ca_xMnO_3

对不同Ca含量的La1-xCaxMnO3 系列样品 (其中 0 .0 5≤x≤ 0 .80 )在室温下进行了正电子寿命谱和多普勒展宽谱的测量 .结果表明 :对应于出现巨磁阻效应的Ca成分范围 (0 .30≤x≤ 0 .5 0 ) ,正电子的平均寿命τm 和多普勒谱S参数明显降低 。

The ceramic samples with nominal composition of La 1- x Ca x MnO 3 (0.05≤ x ≤0.80) are prepared by the ordinary solid state reaction method. The room temperature positron lifetime spectra and Doppler broadening radiation spectra are measured. The Ca content dependence of the mean lifetime τ m and S parameter are performed, which is shown that the τ m and the S parameter decreases with the increase of x in the range from 0.30 to 0.50 caused by localization of electrons. The results show the correspondence between electronic structure and CMR effect.