摘要
采用磁控溅射的方法制备了结构为Ta(5 nm)/Mg O(6 nm)/Ni Fe(t_(NiFe))/Mg O(4 nm)/Ta(3 nm)的磁性多层膜,Ni Fe的厚度t_(NiFe)从5 nm增加到100 nm,之后在真空退火炉中经过400℃,1 h的退火处理并且进行随炉冷却,整个过程中沿着薄膜易轴方向施加大约4378 A·m-1的磁场。采用四探针的方法来测量平面霍尔电压(PHE)和相对电阻变化率,通过X射线衍射(XRD)和高分辨透射电子显微镜(HRTEM)来分析多层膜退火前后的微结构变化。研究结果表明:对于制备态和退火态的Ta/Mg O/Ni Fe/Mg O/Ta纳米磁性多层膜结构,当t_(NiFe)<40 nm时,霍尔输出电压骤减,随着t_(NiFe)的继续增加,霍尔电压基本保持不变。然而,所有的制备态同一厚度的样品经过退火处理之后,霍尔电压都有一定程度的提高,当t_(NiFe)=5 nm时,平面霍尔输出电压增加最大。随着Ni Fe厚度的继续增加,退火处理所导致的输出电压的提高幅度逐渐减小,当t_(NiFe)=100 nm时,霍尔电压退火之后几乎保持不变。不同Ni Fe厚度的样品,霍尔电压经退火处理后之所以提高幅度不同,主要与两个因素有关,一是Mg O/Ni Fe异质界面会增强电子自旋相关散射提高PHE输出电压,二是Ni Fe层因分流也会导致PHE输出电压下降。
The magnetic multilayer Ta（5 nm）/MgO（6 nm）/NiFe（tNire）/MgO （4 nm）/Ta（3 nm） with NiFe thickness ranging from 5 nm to 100 nm was deposited by magnetron sputtering. Then, the samples were annealed for 1 h at 400℃ in a vacuum furnace and cooled to room temperature. During the annealing treatment, the fixed magnetic field was applied in the direction of easy axis of film. In addition, the planar Hall voltage （PHE） and resistivity change were measured by standard four-probe and the microstructure change of magnetic films was characterized by high resolution transmission electron microscope （HRTEM） and X-ray diffraction （XRD）. The results showed that the planar Hall voltage decreased greatly when tNiFe 〈 40 nm and nearly kept constant with the increase of the thick- ness of NiFe for the as-deposited and annealed magnetic muhilayer with Ta/MgO/NiFe/MgO/Ta. The planar Hall voltage would in- crease with some degree for the as-deposited samples with same thickness after annealing and increased largely when tNiFe = 5 nm. With the NiFe thickness increasing, the increment of planar Hall voltage brought by annealing would become smaller and nearly had no change when tNiFe = 100 nm. The increment of planar Hall voltage as function of the NiFe thickness caused by two factors as following： MgO/NiFe heterogeneous interface could enhance the spin-dependent scattering which could increase the planar Hall voltage; and the shunt current would cause the decrease of planar Hall voltage.
出处
《稀有金属》
EI
CAS
CSCD
北大核心
2016年第6期581-585,共5页
Chinese Journal of Rare Metals
基金
国家自然科学基金项目(51331002
51371027)资助
