蒸发-气体-聚集制备的Co-Ag颗粒膜微观结构与巨磁电阻特性

MICROSTRUCTURE AND GIANT MAGNETORESISTANCE OF Co-Ag GRANULAR FILMS DEPOSITED BY EVXPORATION-GAS-AGGREGATION

基于溅射－气体－聚集（SGA）形成纳米金属颗粒的原理，提出了蒸发－气体－聚集（EGA）共沉积制备CO－Ag颗粒膜的新方法，并利用该方法制备了系列Co－Ag颗粒膜样品．TEM／ED分析表明，制备态样品中CO颗粒被Ag原子所包裹，能有效地阻止颗粒的表面氧化与团聚；＃膜无需经过热处理即可形成Co与Ag的相分离，其结构为fcc—Co和fcc-Ag非均匀相多晶共存形态；与Co大块材料相比，薄膜中Co颗粒晶格常数随颗粒大小变化而呈现出不同程度的收缩效应，当颗粒平均直径为8nm时，其晶格收缩量为7％．磁电阻测量结果表明，薄膜在室温下呈现出较大的巨磁电阻效应；随着薄膜中Co颗粒尺寸的减小，其巨磁电阻效应增强．

A novel method, i.e. evaporation-gas-aggregation(EG co- deposition for the preparation of Co-Ag granular films is developed in this paper. TEM analysis shows that Co particles are wellencapsulated in Ag coatings and in polycrystal form with fee-Co and fee-Ag in as-prepared samples,in which surface oxidation and self-aggregation of Co particles could be avoided effectively. Comparedwith the bulk Co, the lattice constant of Co particles is shrinking in different degree depending on particlesize, and the shrinking amount is 7% for Co particles being sum in average diameter. Magnetoresistancemeasurement reveals that the samples show relative large giant magnetoresistance (GMR) at 300K, and theGMR increases with the decrease of particle size in the films.