Studies Of Co/Pd Multilayers And Bit-patterned Media For Magnetic Recording Application

We are living in an information society. With the rapid growth of the demand of data storage, the development of advanced information storage technology, which has features of high performance, low cost, and nonvolatility, are of great importance in our21st century. Magnetic recording technology, due to its stability, high areal density, low price, has been the most popular information storage technology since its birth. In this dissertation, we are focused on Co/Pd multilayers-a new type magnetic media for perpendicular magnetic recording application. Co/Pd multilayers system has its flexibility for different applications because of its easily-tunable magnetic properties such as coercive field and magnetic anisotropy. Co/Pd multilayers can be applicable for both conventional perpendicular magnetic recording and bit patterned media(BPM)-which has been supposed to be a promising candidate for the next generation recording technology. We have prepared well-performing Co/Pd multilayer samples and detailedly studied some key parameters that may have great influence on Co/Pd magnetic properties such as Co thickness, Pd thickness, substrate, seed layers(Pd, Ta/Pd), etc. We also patterned Co/Pd multilayers via e-beam lithography and ion beam etching method. The difference of coercivity and switching field distribution(SFD) between continuous film and BPM media was also investigated. The main results are stated as follows:1.When Co thickness are less than0.8nm, the film shows interface anisotropy which is perpendicular to the film surface. With the Co thickness become thicker, the magnetic moment of multilayers grows rapidly and fee Co/Pd(111) shift to high angle direction. In the mean time, coercivity and nucleation field(absolute value) decrease. When Co=0.3nm, the film coercivity get its maximum value and best squareness. The change of coercivity is mainly ascribed to the trade-off among demagnetization energy, interface anisotropy and stress-induced anisotropy.2.The thickness of Pd layer can also influence the coercivity greatly, but not as that of Co layer. When Pd=1.2nm, coercivity get its maximum, and this thickness of Pd layer is about5atom stacks.3.Film coercivity become larger when seed Pd layer become thicker. The film get its best squareness when Pd=2nm, thicker seed Pd layer can induce well columnar structure and stronger (111) texture, which resulted in the coercive field increase.4.When Ta=2nm, the film with Si(100) substrate has a minimum coercive field and best squareness which indicate that seed Ta with2nm thickness can induce highly exchange coupled films. Ta has slight influence on the intensity of Co/Pd(111) texture when the film was deposited on glass substrate. In contrast, on Si(100) substrate, the intensity of Co/Pd(111) texture decrease remarkable as well as coercivity when Ta=2nm. We also found that Ta=2nm seed layer is smoother than other seeds, which lead to better squareness and lower coercivity.5.When the samples are patterned to be BPM, The coercivity of multilayers increase from1500Oe to2100Oe. Every bit is a single domain, and the coercive mechanism has a strong relationship with etching process and the magnetic properties of continuous film. The switching field distribution(SFD) decrease from466Oe to224Oe, indicate that there is only small dipolar interaction between the bits of BPM.