Fe-Al_2O_3纳米颗粒膜的巨磁电阻效应及微结构

采用磁控溅射方法在玻璃基片上制备了一系列的 Fe- Al2 O3 颗粒膜样品 ,对样品的巨磁电阻效应 (GMR)和磁性能进行了测量 ,并用高分辨电镜 (HRTEM)对膜中 Fe颗粒的微结构进行观察 .结果表明 :磁电阻 MR随 Fe含量而变化 ,在体积分数为 47%时获得最大值 4.0 % .45 % Fe-Al2 O3 颗粒膜的室温磁性表现为超顺磁性 ,磁电阻 MR与 - (M/Ms) 2 成正比 ,相关常数 A≈ 0 .0 3 6 .HRTEM观察表明 ,当 Fe颗粒尺寸约小于 1 nm时 ,Fe颗粒为非晶态 ,而大于该尺寸时则为晶态 .在 Fe- Al2 O3 颗粒膜体系中存在与隧道相关的 GMR,GMR的起因可归于传输电子的自旋相关的散射

Giant Maganetoresistance and Microstructure of Fe-Al_2O_3 Nanogranular Films

A set of Fe Al 2O 3 granular film samples were prepared with a magnetron controlled sputtering method. The GMR effect and magnetic properties were measured and the microstructures of Fe particles were observed by high resolution transmission electron microscope (HRTEM). The result shows that the MR changes with Fe content and reaches the maximum value of 4.0% at 47% Fe. The magnetic properties of Fe(45%) Al 2O 3 exhibit superparamagnetic nature, meanwhile, the MR ratio is proportional to -( M/M s) 2 and the related constant A is about 0.036. From the HRTEM image, it is clear that when the grain size is less than 1 nm, Fe particle exhibits amorphous, while the size is more than 1 nm, it is crystallized. There exists the tuneling dependent giant magnetoresistance effect in Fe Al 2O 3 granular film. The GMR effect mainly originates from the conducting electron's spin dependent scattering.