Ni80Fe20/Cu磁性多层膜中柱晶结构的HRTEM研究

具有巨磁电阻效应(GMR)的磁性金属多层膜在信息存储领域有广阔应用前景(如磁记录读出磁头)并被广泛研究.人们通过离子束溅射、磁控溅射及电子束蒸镀等方法制备了NiFe/Cu多层膜,并进行了许多结构和性质方面的研究[1,2].结果表明,NiFe/Cu多层膜的GMR特性与微结构有密切关系.目前,有关NiFe/Cu多层膜透射电镜显微结构研究的报道很少.     

Magnetic property and interlayer segregation in spin valve metal multilayers

The experimental results show that the exchange coupling field of NiFe/FeMn for Ta/ NiFe/FeMn/Ta multilayers is higher than that for the spin valve multilayers Ta/NiFe/Cu/NiFe/FeMn/ Ta. In order to find out the reason, the composition and chemical states at the surfaces of Ta( 12nm)/ NiFe(7nm), Ta( 12nm)/NiFe(7nm)/Cu(4nm) and Ta( 12nm)/NiFe(7nm)/Cu(3nm)/NiFe(5nm) were studied using the X-ray photoelectron spectroscopy (XPS). The results show that no elements from lower layers float out or segregate to the surface for the first and second samples. However, Cu atoms segregate to the surface of Ta(12nm)/NiFe(7nm)/Cu(3nm)/NiFe(5nm) multilayers, i.e. Cu atoms segregate to the NiFe/FeMn interface for Ta/NiFe/Cu/NiFe/FeMn/Ta multilayers. We believe that the presence of Cu atoms at the interface of NiFe/FeMn is one of the important factors causing the exchange coupling field of Ta/NiFe/FeMn/Ta multilayers to be higher than that of Ta/NiFe/Cu/NiFe/ FeMn/Ta multilayers.     

织构和界面粗糙度对NiFe/FeMn双层膜交换偏置场的影响

采用磁控溅射方法制备NiFe/FeMn双层膜（分别以Ta、Cu作为缓冲层，Ta作为保护层）。实验发现，以Ta为缓冲层的NiFe/FeMn双层膜的交换偏置场比以Cu为缓冲层的NiFe/FeMn双层膜的交换偏置场大，而矫顽力却很小。我们从织构、界面粗糙度两方面对其中的原因进行了分析。以Ta为缓冲层的NiFe/FeMn双层膜有好的织构且NiFe/FeMn界面较平滑，这引起了较强的交换偏置场和较低的矫顽力。     

插层Bi对NiFe/FeMn双层膜交换偏置场的影响及其XPS分析

在Ta／Cu／NiFe／FeMn／Ta薄膜中,我们曾发现Cu在NiFe层的表面偏聚导致NiFe／FeMn薄膜的交换偏置场降低。为了抑制Cu的表面偏聚,我们在Ta／Cu／NiFe／FeMn／Ta薄膜中在Cu／NiFe界面沉积Bi插层。实验发现,沉积适当厚度的Bi插层可以将NiFe／FeMn双层膜的交换偏置场提高1倍。XPS分析表明,在Cu／NiFe界面沉积的插层Bi有效地抑制了Cu在NiFe表面的偏聚,提高了交换偏置场。     

镜面反射纳米氧化层自旋阀的显微结构研究

巨磁电阻 (ＧＭＲ)多层膜自发现[1] 以来 ,自旋极化电子的传输过程一直是凝聚态物理研究的热点。如何进一步改进材料 ,提高巨磁电阻效应 ,已成为自旋阀在计算机硬磁盘读出磁头等重要信息处理器件方面应用的关键问题。最近 ,通过将自旋阀的部分被钉扎层和自由层进行氧化处理 ,引入厚度约为1ｎｍ的氧化层薄膜 (ＮＯＬ ,ｎａｎｏ ｏｘｉｄｅｌａｙｅｒ) ,可成倍地提高自旋阀的巨磁电阻 (ＧＭＲ)比率[2 ] 。这一发现引起了国际自旋电子学研究领域的广泛关注[3～ 6] 。目前 ,人们普遍认为厚度为 2～ 3原子层的纳米氧化层对自旋极化电子产生镜面反…     

Cu88Co12合金的巨磁电阻及其微结构的研究

本文利用场离子显微镜－原子探针及电镜研究了具有巨磁电阻效应的甩带Ｃｕ８８Ｃ ｏ１２合金的微结构。Ｃｕ８８Ｃｏ１２合金经４５０℃退火半小时后发邓有明显的巨磁电阻。     

高精度金属薄膜磁电阻效应测试系统

概述了探针法金属薄膜磁电阻效应测试的原理;分析了探针因子对测量结果的影响;设计组装了金属薄膜磁电阻效应的高精度测试系统,并给出了微机控制软件的关键子程序。该系统集数据采样、数据处理、参数计算等功能于一体,用户界面友好、测试范围宽、精度高。系统软件还能显示和打印测量结果的数据曲线,并可生成标准数据文件供OR IG IN等数据处理软件调用。     

界面掺杂FeMn对CoFe/CrPt交换偏置体系的影响

采用磁控溅射的方法制备了CoFe/CrPt钉扎的交换偏置体系,用外加磁场真空退火以获得钉扎场.通过把反铁磁的FeMn掺入到该钉扎体系中发现,约0.7nm厚度的FeMn掺入在CoFe/CrPt的界面时,可以使体系的钉扎场从原来的5.6×103A/m增加到1.55×104A/m,而体系的Blocking温度仍然可以达到600℃.     

Interface chemical states of NiO/NiFe films and their effects on magnetic properties

Ta/NiOx/Ni81Fe19/Ta multilayers were prepared by rf reactive and dc magnetron sputtering. The exchange coupling field ( Hex) and the coercivity ( Hc) of NiOx/Ni81Fe19 as a function of the ratio of Ar to O2 during the deposition process were studied. The composition and chemical states at the interface region of NiOx/NiFe were also investigated using the X-ray photoelectron spectroscopy (XPS) and peak decomposition technique. The results show that the ratio of Ar to O2 has great effect on the nickel chemical states in NiOx film. When the ratio of Ar to O2 is equal to 7 and the argon sputtering pressure is 0.57 Pa, the x value is approximately 1 and the valence of nickel is + 2. At this point, NiOx is antiferromagnetic NiO and the corresponding Hex is the largest. As the ratio of Ar/O2 deviates from 7, the exchange coupling field ( Hex) will decrease due to the presence of magnetic impurities such as Ni +3 or metallic Ni at the interface region of NiOx/NiFe, while the coercivity ( Hc) will increase due to     

插入Bi层对NiFe/Cu/NiFe/FeMn自旋阀多层膜交换耦合的影响

对于NiFe/Cu/NiFe/FeMn自旋阀多层膜，Cu原子偏聚到NiFe/FeMn界面将导致自旋阀多层膜中NiFe/FeMn的交换耦合Hex下降，然而，少量的表面活化原子Bi被沉积到Cu层和被钉扎NiFe层之间。Cu原子在NiFe/FeMn界面的偏聚可以被抑制。而且，更重要的是Ta/NiFe/Cu/NiFe/FeMn/Ta自旋阀多层膜中的交换耦合场Hex可以被有效地提高。