【作者】 潘宇超；

【导师】 张卫国；

【作者基本信息】 天津大学 ， 应用化学， 2009， 硕士

【摘要】 对于自旋阀的研究主要采用CPP(电流垂直于膜面)和CIP(电流平行于膜面)这两种方式。目前自旋阀CIP-GMR的实际值已经接近理论极限,因而对于自旋阀CPP-GMR理论研究和优化更具现实意义。论文以阳极氧化铝(AAO)为模板,采用控电位电沉积法制备了Co、NiFe磁性纳米线阵列。在此基础上,采用双槽控电位电沉积法制备了[NiFe/Cu/Co/Cu]_n多层纳米线。利用扫描电镜(SEM)、透射电镜(TEM)和XRD对纳米线进行表征。通过振动样品磁强计(VSM)测试样品的磁性能。研究表明,沉积电位为-0.95V时,所得Co磁性纳米线阵列具有良好的硬磁性。Co纳米线为六方密排(hcp)结构,且单晶六方密排(hcp)钴纳米线的c轴在垂直于线轴的方向有择优取向。低温(300°C)退火处理有利于改善Co的磁性能,高温(400°C、500°C)退火处理不利于改善Co的磁性能。沉积电位为-1.0V时,所得NiFe磁性纳米线阵列具有良好的软磁性。NiFe纳米线为面心立方(fcc)Ni固溶体。退火处理对于改善NiFe的磁性不利。500°C下退火处理后的NiFe纳米线为面心立方(fcc)Ni固溶体和六方密排(hcp)Fe析出相的共存体。多层纳米线阵列粗细均匀,长径均一。多层纳米线的长度可以达～20μm。测得了[NiFe(5nm)/Cu(tCunm)/Co(5nm)/Cu(tCunm)]_n的磁滞回线,与模拟曲线对比知,多层纳米线中,Co层的难磁化轴平行于模板平面,致使多层纳米线的剩磁比偏低。此外,本论文对CPP-GMR的理论模型进行了综述,介绍了计算自旋阀CPP-GMR的方法。更多还原

【Abstract】 The giant magnetoresistance(GMR) of spin valves has been investigated in two main geometries:the current in plane(CIP) geometry and the current perpendicular to plane geometry. It seems that now the CIP GMR of spin valves has reached its upper limits. As a result,the CPP GMR of spin valves is more promising in terms of both theoretical study and commercial product.Ordered cobalt nanowire arrays and NiFe nanowire arrays were electrodepositioned into the pores of AAO membranes. [NiFe/Cu/Co/Cu]_n multilayered nanowires were prepared by controlled electrodeposition from two different solutions using nanoporous aluminum oxide membranes. The morphology,structure and magnetic properties of the nanowires were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), vibrating sample magnetometer(VSM),respectively.Cobalt nanowire arrays prepared at -0.95V appeared fine retentiveness. The structure of cobalt is hcp with a c-axis oriented almost perpendicular to the wire. The study of the effects of annealing on the CPP-GMR showed that low temperature is beneficial to cobalt,while high temperature is adverse.NiFe nanowire arrays prepared at -1.0V appeared well soft magnetism. The structure of NiFe is fcc. The study of the effects of annealing on magnetism of NiFe was also made. The NiFe nanowire annealed at 500°C was a mixture of nickle solid solution and iron.The multilayered nanowire arrays were regularly arranged. The multilayered nanowire could be as long as～20μm。Comparing the Hysteresis loops of [NiFe/Cu/Co /Cu]_n multilayered nanowires with the modeled Hysteresis loops, we came to the conclusion that Co layers of [NiFe/Cu/Co/Cu]_n has in-plane hard magnetization axis,which resulted in low remanence ration .The theoretical models of the CPP-GMR were reviewed,and a method for the calculation of CPP-GMR of spin valves was introduced.更多还原