利用FePt/Au多层膜结构制备垂直磁记录L1_0-FePt薄膜

Preparation of L1_0-FePt film for perpendicular magnetic recording media by using FePt/Au mutilayers

利用磁控溅射方法在100℃的MgO单晶基片上制备了[FePt/Au]10多层膜,并研究了采用FePt/Au多层膜结构对FePt薄膜的有序化温度、矫顽力(HC)、垂直磁各向异性、晶粒尺寸以及颗粒间磁交换耦合作用的影响.磁性测试结果表明:FePt/Au多层膜在退火后具有较高的HC、良好的垂直磁各向异性、较小的晶粒尺寸且无磁交换耦合作用.截面高分辨电镜分析表明:Au可以缓解MgO和FePt之间较大的晶格错配,从而促进薄膜的垂直磁各向异性;同时,采用FePt/Au多层膜结构增加了FePt/Au界面能、应力能以及Au原子在薄膜中的扩散作用,促进了薄膜的有序化,从而有效降低了有序化温度,并且大幅度提高其HC.此外,Au原子部分扩散到FePt相的边界处,起到抑制FePt晶粒生长、隔离FePt颗粒的作用,从而显著降低了FePt晶粒的尺寸和颗粒间磁交换耦合作用.

FePt/Au mutilayers were deposited on 100℃ MgO（001） single crystal substrate by magnetron sputtering. The influence of the FePt/Au multilayer structure on the ordering temperature, coercivity （Hc ）, perpendicular magnetic anisotropy （PMA）, FePt grain size and interparticle exchange coupling （IEC） of films were studied. Results show that the film possesses high Hc, excellent PMA, small grain size and weak interparticle exchange coupling after annealing. The results of HRTEM reveal that Au can relieve mismatch between MgO and FePt lattices, leading to excellent PMA. Moreover, the FePt/Au interface energy, the stress energy due to the mismatch between FePt and Au lattices and the diffusion of Au atoms promote the ordering of FePt film. This leads to the decrease of ordering temperature and considerable increase of Hc . Au atoms partly diffuse to the boundaries of FePt phase and function as grain finer and particle isolator, which decrease the FePt grain size and IEC.