掺杂锰基氧化物中的相分离和渗流效应  

Phase separation and percolation in doped manganites

作　　者：张留碗[1] 

机构地区：[1]清华大学物理系清华大学先进材料教育部重点实验室,北京100084

出　　处：《物理》2003年第7期445-448,共4页Physics

摘　　要：目前 ,相分离仍是锰基氧化物超大磁电阻材料研究的热点 ,渗流效应假设已广泛用于解释其电输运特性 .作者用变温磁力显微镜首次在La0 .3 3 Pr0 .3 4 Ca0 .3 3 MnO3 薄膜中直接观察到了渗流过程 ,微观上证明了渗流效应假设的正确性 .实验发现 ,降温过程中电阻率的陡降是铁磁金属相的渗流效应引起的 ,升温过程中电阻率的上升 ,则是由导电路径上磁畴的磁化强度随温度的升高而降低引起的 ,而导电路径一直存在 .微观的磁回滞和宏观的电阻回滞相吻合 .当然要定量解释锰氧化物中的超大磁电阻效应还需要做大量的理论和实验工作 .Currently, phase separation is still a hot topic in the study of colossal magnetoresistive materials. Percolation is widely used to explain its temperature dependent resistivity. In this paper, the percolative process has been observed for the first time using a low temperature magnetic force microscope in La 0.33Pr 0.34Ca 0.33MnO 3 thin films. It is found that upon cooling the abrupt decrease in the resistivity is related to the formation of percolation of the ferromagnetic metallic phase in the insulating matrix, while the rapid increase in the resistivity during the warming process is due to the decrease in the magnetization. The microscopic magnetic hysteresis is consistent with the macroscopic resistivity hysteresis. Further work is needed to explain quantitatively the colossal magnetoresistance effect in the doped manganites.

关 键 词：掺杂锰基氧化物 相分离 渗流效应 超大磁电阻材料 超大磁电阻效应 

分 类 号：O482.5[理学—固体物理]