The areal density of hard disk drive using traditional CoCr-based thin films media can not be elevated further because of the super-paramagnetism effect. In order to increase the areal density in magnetic recording system, the studies of new magnetic recording media materials are necessary. In this dissertation, we have studied the possibility of FePt thin films as ultra-high density perpendicular magnetic recording media. Due to its high uniaxial magnetocrystalline anisotropy (7×107erg/cm3), fct-FePt grains could be fined to nanometer-sized while remaining enough thermal stability. Therefore, lager areal density could be realized on these tiny grains.
This dissertation focuses on two aspects. The first is the reduction of transforming temperature of FePt from fcc to fct phase in FePt or FePt-Al2O3 thin films. The actual hard disk manufacture line does not endure the temperature as higher as 500oC~600oC, which is necessary for FePt phase transforming from fcc to fct phase. Hence, the study on reducing the ordering temperature of FePt is very important. In this dissertation, the transforming temperature was reduced to a certain extent by the addition of N2 during sputtering and in-situ ordering. The main results are as follows:
1)15% N2 addition during sputtering can reduce the transforming temperature of FePt phase from fcc to fct phase about 100oC in FePt-Al2O3(15vol.%) thin films. The texture of FePt phase changes from (111) dominant texture to a more random texture due to the N2 addition. Structural analysis reveals that the release of N atoms during the post annealing induces a large number of vacancies in the films, which benefits to the transformation of FePt phase from fcc to fct.
2)The transforming temperature of the FePt films prepared by in-situ ordering is only 250oC, while 400oC for FePt-Al2O3(15vol.%) thin films. Both of the temperatures are 200 oC lower than that of the films prepared by post-annealing.
3)Fine FePt grains with 6nm average diameter were obtained in FePt-Al2O3(15vol.%) films deposited at 400 oC, which accords with the requirement for ultra-high density magnetic recording media. However, the grain size distribution needs to be improved further.
4)The lower ord...