采用磁控溅射方法在玻璃基片上制备了以Ru,Cu,Pt和Ta为底层的Co Fe B/Pt多层膜样品,研究了各底层对Co Fe B/Pt多层膜的反常霍尔效应的影响。发现Ru和Cu作为Co Fe B/Pt多层膜的底层在保持样品的垂直磁各向异性方面的作用远不如Pt和Ta底层,而且样品的霍尔电阻比Pt和Ta做底层要小。Ta作为Co Fe B/Pt多层膜的底层与Pt作为底层相比能够更好地和多层膜晶格匹配,并且在400℃退火后反常霍尔效应得到增强。霍尔电阻提高近80%,矫顽力达到了5.7×10~3 A·m^(–1),有望作为垂直自由层应用到磁隧道结构中。
采用直流磁控溅射法在玻璃基片上制备了Pt底层和MgO/Pt双底层的Co/Ni多层膜样品,通过反常霍尔效应研究了不同MgO厚度和退火温度对样品垂直磁各向异性(perpendicular magnetic anisotropy,PMA)的影响.随着底层中MgO厚度的逐渐增加,样品的矫顽力也随之增强,霍尔电阻变化不大;对样品进行退火处理后发现,单纯Pt底层的Co/Ni多层膜随着退火温度的升高,霍尔电阻逐渐降低,矫顽力则迅速降低,热稳定性较差;而当MgO/Pt双底层的样品在200?C退火后矫顽力大幅增加,霍尔电阻略微有所减小,更高的退火温度使得Co和Ni合金化,导致多层膜的PMA特征减弱.
A series of Cr/SmCo/Cr films with high Sm concentration(37.7at%) were prepared by magnetron sputtering.Effects of SmCo thickness,annealing temperature,and annealing time on magnetic properties and crystal structure were carefully studied.Results show that crystallization degree and phase transition in the films can be controlled by the SmCo thickness and optimized by properly increasing the annealing temperature and extending the annealing time.Finally,a SmCo film with high magnetic properties and low MEI was constructed.
应用磁控溅射法在玻璃基片上制备了以Pt为底层的CoFeB/Ni多层膜结构样品,通过测试样品的反常霍尔效应研究多层膜的垂直磁各向异性(perpendicular magnetic anisotropy,PMA),对影响多层膜垂直磁各向异性的各因素进行了调制.实验结果表明,多层膜的底层厚度、周期层中各层的厚度及周期数对样品的反常霍尔效应和磁性有重要影响.通过对样品各参数的逐步调制,最终获得了具有良好PMA的CoFeB/Ni多层膜最佳样品Pt(4)/[CoFeB(0.4)/Ni(0.3)]_3/Pt(1.0).经测试计算,该样品的各向异性常数K_(eff)为2.2×10~6erg/cm^3(1 erg/cm^3=10^(-1)J/m^3),具有良好的PMA性能,样品总厚度为7.1 nm,完全满足制备垂直磁结构材料的厚度要求,可进一步研究其在器件中的集成与应用.
