摘要:
文章中,通过磁控溅射制备了界面处插入4d,5d元素薄层（包括Ru,Pd,Ag和Au）的Ta/NiFe/Ta多层膜,并对它们的磁输运和磁性以及微结构进行了测试和表征.结果显示,Pd和Pt一样界面效应显著,能有效地提高NiFe薄膜退火前后的AMR比值,并抑制磁性死层.表面能比较小、熔点相对低的插层材料Ag,Au在退火过程中容易通过晶界扩散,强烈破坏其AMR性能.对于熔点高、表面能比较大的插层材料如Ru,磁性死层同样得到了抑制,NiFe薄膜的温度稳定性也可以得到提高.结果表明界面插层从界面电子自旋-轨道散射、界面死层和界面原子扩散等方面深刻影响NiFe薄膜的AMR.
Abstract:
Ta/NiFe/Ta trilayers are commonly used in various commercial sensors based on anisotropic magnetoresistive（AMR） effect.Technologically it is desirable to reduce NiFe film thickness to diminish the demagnetization effect for the smaller and smaller devices.However,the AMR ratio of thin NiFe film decreases rapidly with film thickness decreasing when the NiFe film is thinner than 20 nm.Our previous work revealed that the AMR ratio and the thermal stability of Ta/NiFe/Ta trilayers can be significantly improved through interfacial Pt addition due to the enhanced interfacial spin-orbit scattering and the suppressed magnetic dead layers.In this paper,4d and 5d elements including Ru,Pd,Ag and Au,are also introduced at the interfaces of Ta/NiFe/Ta films fabricated by DC magnetron sputtering.It is found that the insertion of interfacial Pd layers leads to an appreciable AMR enhancement in the as-sputtered state and after annealing.Insertion layers of Ag and Au with small surface energy and relatively low melting point suffer from thermal interdiffusion and seriously deteriorate the AMR of the annealed films,whereas Ru insertion layers exhibit improved thermal stability.The present results indicate that the AMR of Ta/NiFe/Ta films can be notably affected by the extremely thin interfacial insertion layers due to the changed interfacial spin-orbit scattering,magnetic dead layer and atomic interdiffusion.
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