SmCo/Co多层交换弹性纳米晶复合永磁薄膜的制备和磁耦合研究

Preparation and Magnetic Coupling Study of SmCo/Co Exchange Spring Multilayer Nanocomposite Permanent Films

利用磁控溅射的方法,在室温条件的Si基片上制备了[SmCo(25 nm)/Co(x)]4/SmCo(25 nm)多层交换弹性纳米晶复合永磁薄膜(Co层厚度x=0～10 nm),经过550℃/20 min的真空退火处理使薄膜结晶后,进行磁性测试和磁耦合分析。结果表明:SmCo层厚度固定为25 nm时,调整Co层的厚度,从0至10 nm逐渐增加,矫顽力从2270.3 kA·m-1逐渐降低至1040.5 kA·m-1,同时,饱和磁化强度和剩磁随Co层厚度增加逐渐增加,上升了60%。当加入10 nm的Co层后,多层膜的最大磁能积比125 nm的单层SmCo薄膜增加了46%。另外,与SmCo/Co双层交换弹性薄膜在退磁过程中表现的零场附近的软硬磁双相行为相比,SmCo/Co多层交换弹性薄膜表现出单相反转行为,说明体系中的两种磁性层具有更好的磁耦合。经过磁耦合研究发现,当Co软磁层较薄时,薄膜中磁性颗粒以颗粒间交换耦合为主;当软磁层厚度增加时,颗粒间交换耦合减弱,静磁耦合增强,保证了软硬磁相之间的良好磁耦合作用。Co层的加入有效地提高了薄膜的磁性能。

The [SmCo（25 nm）/Co（x）]4/SmCo（25 nm） exchange spring multilayer films were deposited on Si substrates by magnetron sputtering under room temperature,followed by a high vacuum annealing at 550 ℃ for 20 min in order to improve the crystallization of SmCo5 in the films（x,the thickness of Co layers,were adjusted from 0 to 10 nm）.Results showed that the SmCo layers were fixed at 25 nm,when the thickness of Co layers increased from 0 to 10 nm,the coercivity dropped from 2270.3 to 1040.5 kA · m-1,meanwhile,the saturated magnetization and the remanent magnetization increased 60%.When the 10 nm Co layers were inserted,the maximum energy product of the multilayer was increased 46% to the SmCo single layer film.Additionally,different with appearance of kinks in the SmCo/Co bilayer films,a single phase like behavior were observed in the SmCo/Co multilayer films,indicated a better magnetic coupling between layers.The result showed that,intergrain exchange coupling was dominant with thin Co layers,and the magnetostatic coupling was predominant with thick Co layers,both of them ensured the good magnetic coupling between the hard and soft layers.The addition of Co layers improved the magnetic properties of the films effectively.