摘要
磁记录存储系统中通常使用复合磁头，它包含两部分：一是写入信息的软磁薄膜写磁头，另一个是读取信息的GMR读磁头。这两部分性能的优劣直接影响磁记录系统的记录性能。本论文主要以下对三部分进行了研究：一是GMR读磁头用水平取向CoCrPt硬磁偏置层的研究；二是FeCo反铁磁耦合薄膜的研究；三是FeCoN软磁薄膜的研究。主要的到了一下结果：
1．直接沉积在(200)取向的CrW衬底上的CoCrPt薄膜并没有出现期望的(11(?)0)水平取向，而是(0002)垂直取向。引入一层3 nm的CoCr中间层后，我们得到了不同Pt原子百分比(8．5-25 at％)的(11(?)0)水平取向的CoCrPt薄膜。CoCr中间层层对于调整衬底层与磁性层之间的错配度，促进外延生长起到了关键作用。
2．我们利用3维微磁学模型对于CoCrPt水平矫顽力的机理进行了研究，发现CoCrPt水平矫顽力是由磁晶各向异性能和磁弹性各向异性能两项决定的，当Pt的原子百分比大于15％时，CoCrPt薄膜的面内矫顽力主要由磁弹性各向异性能决定。
3．我们在MgO籽层和Cr衬底上成功制备了水平取向的CoCrPt薄膜。
4．在FeCo薄膜中添加了N元素后，薄膜的软磁性大为改善。薄膜的磁性随着N_2流量比fN的值的变化而变化。当N_2流量比fN的值为10％时，薄膜的磁性最好为：4πMs～-20 kG，H_(ce)～4．5 Oe，H_(ch)～1 Oe，H_k～90 Oe。N_2流量比fN的值为11％是，薄膜矫顽力最小为：H_(ce)～3Oe，H_(ch)～0．45 Oe。N_2流量比fN的值在9％-18％之间时，FeCoN薄膜都保持良好的软磁性，H_(ch)的值为1 Oe左右。
5．FeCoN薄膜有非常优异的高频响应特性，当N_2流量比，fN的值为10％时，我们得到最高的铁磁共振频率为3．45 GHz。6．FeCo单层膜和FeCoN薄膜的磁性相比较是由两种不同的磁化过程决定的，FeCo单层薄膜是团簇的磁化过程；而FeCoN薄膜是均匀的颗粒，它的矫顽力的显著降低可以归因于晶粒尺寸效应。
7．我们利用Ru做非磁性金属中间层制备了FeCo反铁磁耦合薄膜。在Ru层厚度为0．88 nm，反铁磁耦合薄膜的耦合最强。但薄膜的磁性并不是很好，难轴矫顽力为20 Oe。
8．我们利用磁力显微镜观测薄膜表面的磁畴变化，研究了薄膜的反磁化过程。多层薄膜沉积态是上下两层对应分畴的，磁化到饱和后所有磁矩都沿外场反向排列。随着外场的降低薄膜上层磁性层先开始出现反向畴，开始翻转。当磁场降至反向40 Oe时，薄膜上层的磁畴几乎完全翻转，只有少部分由于缺陷的存在而被钉扎。反向磁场继续增大，下层磁性层磁矩开始分畴翻转。当磁畴增加至反向650 Oe时，上下两层磁性层磁矩都已翻转沿外场方向排列。即多层膜上层磁矩先随外场的降低开始分畴翻转，上层翻转后下层再开始翻转。
Generally,magnetic recording system uses compound magnetic head,itincludes two parts:The soft magnetic writing head and the GMR reading head.The performances of the two parts influence the capability of the magneticrecording system directly.In this thesis,our research work have three parts:thefirst part is researching of longitudinally oriented CoCrPt thin film for GMR readhead using; the second part focus on FeCo antiferromagnetic exchange couplingmultilayer; the third part focus on FeCoN soft magnetic thin films.The results areas follows:
1.The CoCrPt thin film deposited on CrW underlayer with (200) texturedirectly did not show (11(?)0) longitudinally orientation we expected,but the(0002) perpendicular orientation.When a 3 nm CoCr intermediate layer wasintroduced,we got (11(?)0)longitudinally orientation CoCrPt thin film with Ptatom percent raised from 8.5% to 25%.The CoCr intermediate layer playedan important role to modulate the misfits between the magnetic layer and theunderlayer.
2.We built up a three-dimensional micromagnetic model,with carefuldiscussions of the uniaxial crystalline anisotropy and the magnetostriction.Itwas found that the coercivity mechanisms of the CoCrPt thin films aredominated by the magnetostriction effects when the Pt content is more than15 at%.
3.We fabricated longitudinally CoCrPt thin film on MgO seed layer and Crunderlayer successfully.
4.The addition of N element into FeCo thin film could improve the softmagnetic performance.The magnetic properties of the thin film changedalong with N_2 flux ratio.When the N_2 flux ratio was 10%,it had the bestproperties:4πM_s～20 kG,H_(ce)～4.5Oe,H_(oc)～1Oe,H_k～90 Oe.When the N_2flux ratio was 10%,it had the lowest coercivity:H_(ce)～3Oe,H_(ch)～0.45 Oe.N_2flux ratio raised from 9% to 18%,FeCoN thin film kept excellent softmagnetic properties,the coercivity on the hard axis kept about 1Oe.
5.FeCoN thin films have excellent high frequency performance.When the N_2flux ratio was 10%,we got the highest ferromagnetic resonance frequency as 3.45 GHz.
6.FeCo thin film and FeCoN thin film had different magnetization process.FeCo thin film was cluster structure,so the magnetization process was clustermagnetization mode.FeCoN thin film was symmetrical grain structure,thereduction of coercivity of FeCoN thin could attribute to grain size effect.
7.We prepared FeCo antiferromagnetic exchange coupling multilayer with Runon-magnetic metallic intermediate layer.When the thickness of Ru layer was0.88 nm,the multilayer had the strongest exchange coupling energy.But themagnetic performance of the multilayer was not good; the coercivity on thehard axis was about 20 Oe.
8.We used magnetic force microscope to study the reverse process.As-deposited multilayer divided into some domain and the domain in theupper and bottom layer were corresponding.When the multilayer magnetizedsaturation,all the magnetic moment arrayed along the applied field.Alongwith decreasing and reversing of the applied field,the upper layer appearedmagnetic domain and magnetic moment reversed first.When the all magneticmoment of upper layer except a little nailed by the disfigurement reversed,the bottom layer began to appeared magnetic domain and the magneticmoment reversed then.
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