高自旋极化氧化物材料的颗粒边界磁电阻效应

颗粒边界磁电阻是高自旋极化氧化物颗粒体系中由于颗粒边界的存在而导致显著的磁电阻效应。本文将这种磁电阻效应定义为颗粒边界磁电阻效应。这里所说的颗粒边界，包括各种自然和人工晶界、粉末颗粒表面、复合材料中的颗粒界面等多种情况；所涉及的材料包括高自旋极化氧化物多晶、压缩粉末和各种复合材料等。对颗粒边界磁电阻效应的研究，不仅有助于人们进一步理解高自旋极化氧化物磁输运性质的基本机制，并为寻求具有高磁电阻效应的新型自旋电子学器件提供理论基础。本文综述了高自旋极化氧化物颗粒边界磁电阻研究的主要背景和发展现状，介绍了该领域中主要的实验发现和理论模型，展望了未来的发展。

GRAIN-BOUNDARY MAGNETORESISTANCE IN HIGH SPIN-POLARIZED OXIDES

Grain-boundary magentoresistance is the magnetoresistance effect due to the existence of lots of grain boundaries in granular systems composed of high spin-polarized oxides.The "grain boundaries" herein include not only natural grain boudaries observed in polycrystalline samples but also those in artificial grain-boundary junctions,grain surfaces in pressed powders,and in various composites based on oxides with high spin polarization.Studies on grain boundary magentoresistance give an insight into the underlying transport mechanisms in high spin-polarized materials,and offer possible approaches to realize better magnetoresistance effects and new electronic devices.The background and improvements in this field is reviewed in the present paper.Both experimental results and theoretical models for grain boundary magnetoresistance are presented.A discussion of the unresolved problems and the further developments concludes this review.