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摘要铁磁/反铁磁薄膜体系的交换偏置效应在自旋阀结构和磁性隧道结领域具有广泛的应用。本文利用高真空磁控溅射平台制作了Co/FeMn和FeCo/IrMn样品，然后通过VSM和SQUID对样品的磁滞回线等磁性能进行研究，对交换偏置效应进行验证。28727
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对于Co/FeMn薄膜体系，其室温磁滞回线，易轴方正、难轴倾斜，即具有较好的软磁性能；但易磁化轴没有发生偏移，即没有生成交换偏置；分析得到可能是FeMn的反铁磁耦合较弱，导致薄膜无法产生交换偏置。
而对于FeCo/IrMn薄膜体系，采取6层镀膜，样品磁滞回线易轴出现明显的偏移，形成交换偏置。我们通过分析镀膜条件，得出交换偏置场的最适膜厚度。
但是通过研究在实验中我们发现：
（1）Co/FeMn薄膜体系的各向异性场Hk较小，均在100Oe以下，而交换偏置的多层周期薄膜各向异性场最大为Hk=342.04Oe，这是由于FeMn反铁磁耦合较IrMn的反铁磁耦合弱。在反铁磁层厚度从小到大的变化过程中铁磁层的矫顽力出现一峰值。
（2）通过调节IrMn膜厚可以诱导发生交换偏置效应。FeCo的有效各向异性和矫顽力大小随IrMn膜厚先增加后减小，本文中当SiO2/ [IrMn/FeCo]3周期薄膜中每层IrMn膜厚为10 nm时，各向异性和矫顽力出现最大值。
关键词 交换偏置；铁磁；反铁磁；各向异性
毕业论文设计说明书外文摘要
Title Tuning Anisotropy of Soft Magnetic Metallic Multilayer Film Based on Exchange Bias Effect
Abstract
The exchange bias in FM/AFM bilayers has been widely used in spin valve structures and magnetic tunnel junctions. In this paper we manufactured Co/FeMn and FeCo/IrMn film system by high vaccum magnetron sputtering platform. Then we investigated hysteresis loop and verified the exchange bias by VSM and SQUID.
For Co/FeMn film system, the hysteresis loops at room temperature have good soft magnetic properties; But no offset easy axis of magnetization occurs, that does not generate exchange bias; There is no exchange bias can we find, we analysis it might because antiferromagnetic coupling of FeMn is weak.
While for FeCo/IrMn film system, we manufacture six layers of film. There is an obvious offset on hysteresis loop, namely exchange bias.
However, during the process of experiment, we occasionally found:
(A) For Co/FeMn film system，anisotropic field is below 100 Oe. While the anisotropic field of exchange bias seasonal film system can reach 342.04 Oe. It is mainly because the antiferromagnetic coupling of FeMn is weaker than IrMn. The coercivity of ferromagnetic layers reach its maximum when the thickness of antiferromagnetic layer increase.
(B) We can control exchange bias and the coercivity of the system by controling the thickness of the IrMn layer. Effective anisotropy and coerciy of FeCo increase first then decreases with the increase of thickness of IrMn layer. In this paper when the thickness of IrMn is 10nm, anisotropy and coercivity reach their maximum.
Keywords: Exchange bias; Ferromagnetic; Antiferromagnetic; Anisotropy;
目 次
1 绪论 1
1.1 课题背景 1
1.2 铁磁/反铁磁交换偏置的基本特征 2
1.3 交换偏置理论解释模型 6
1.4 交换偏置中反铁磁稀释效应的研究 8
1.5 选题目的以及研究内容 9
2 实验材料的制备和研究方法 11