利用金属有机物分解法在石英衬底上制备了多晶La0.67Ca0.33MnOz薄膜.研究了薄膜输运特性及其与温度的关系,发现薄膜的金属-半导体转变温度Tp(约172K)远低于其居里温度(约247K);在平行于膜面的1T磁场下,77K～302K温度范围内,没有磁电阻(MR)峰,而是在Tp温度以下,有一宽的平台,平台处MR值约为21%～24%,在Tp温度以上,MR随温度上升而迅速降低;在77K温度下,薄膜具有显著的低场磁电阻效应.上述磁输运特性与载流子在晶界附近的输运行为如强的自旋相关散射和晶粒间自旋极化隧道效应等有关.在77K温度下,还观察到了退磁效应引起的磁电阻垂直备向异性.
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