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61.
MnBi compound is fabricated under a magnetic field of 1 T, and the c-axis of hexagonal MnBi crystal is aligned parallel to the magnetic field direction. The saturation magnetization Ms decreases with the increase of temperature. At temperatures below 20OK, the coercive field Hc is about 150Oe, while the coercive field Hc increases with temperature above 200K. From 200K to 300K, the remnant magnetization Mr and the Mr/Ms increase with the temperature. Below 200K, Mr and Mr/M8 reach roughly a constant value. However, there is an abnormal increase at 100 K in He, Mr and Mr/Ms, which comes from a spin-reorientation in MnBi. Magnetization results show the spin-reorientation for MnBi at about 91 K due to the variations of the anisotropy constants. 相似文献
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64.
利用磁控溅射方法沉积双势垒磁性隧道结多层膜, 其中Al-O势垒层由等离子体氧化1 nm厚的 金属铝膜方式制备,然后采用深紫外光曝光和Ar离子刻蚀技术、微加工制备出长短轴分别为 6和3 μm大小的椭圆形双势垒磁性隧道结(DBMTJ),并在室温和低温下对其自旋电子输运 特性进行了研究. DBMTJ的隧穿磁电阻(TMR)比值在室温和42 K分别达到27%和423%, 结电阻分别为136 kΩ·μm2和175 kΩ·μm2,并在实验中观 察到平行状 态下存在低电阻态及共振隧穿效应,反平行态下呈现高电阻态以及TMR随外加偏压或直流电 流的增加而发生振荡现象. 由此,设计了一种基于这种双势垒磁性隧道结隧穿特性的自旋晶 体管.
关键词:
双势垒磁性隧道结
隧穿磁电阻
共振隧穿效应
自旋晶体管 相似文献
65.
利用金属掩模法和Ir22Mn78合金反铁磁钉扎层,制备了四种钉扎型的Py/Al2O3/Py,Py/Al2O3/Co,Co/Al2O3/Py和Co/Al2O3/Co磁性隧道结,坡莫合金的成分为Py=Ni79Fe21.例如:利用狭缝宽度为100?μm的金属掩模,直接制备出室温隧穿磁电阻比值为17.2%的磁性隧道结Co/Al2O3/Co,其结电阻为76Ω,结电阻和结面积的积矢为76×104Ωμm2,自由层的偏转场为1114?A/m,并且在外加磁场0.1114A·m-1之间时室温磁电阻比值
关键词:
磁性隧道结
隧穿磁电阻
磁随机存储器
金属掩模 相似文献
66.
本文通过物理模拟的方法研究了强磁场复合交变电流作用对过偏晶合金凝固组织的影响机理,考察了电磁复合场下第二相初生液滴直径的演变规律,以及洛伦兹力作用下已分层少数相被"打碎"进入基体相的过程.结果表明:电磁体积力的增加,有利于液滴初始直径的减小;而交变电流频率的影响存在最佳值,偏离该值对初生液滴直径的抑制效果下降,这与实际试验规律一致;在电磁复合场作用下,已经分层的两液相可以重新实现均匀混合.这些效应有效缓解了偏晶合金凝固前第二相由于各种因素导致的偏聚,模拟结果直观地揭示了电磁复合场制备匀质偏晶合金的主要机理
关键词:
电磁复合场
偏晶合金
物理模拟 相似文献
67.
Jie-Feng Gao Hua-Dong Huang Ding-Xiang Yan Peng-Gang Ren Xiang-Bu Zeng Zhong-Ming Li 《Journal of Macromolecular Science: Physics》2013,52(6):788-796
The electrical properties of anisotropic carbon nanotubes (CNTs)/polycarbonate (PC)/ polyethylene (PE) (ACPC) strongly depended on the CNTs’ concentration. When the ACPC was subjected to isothermal treatment (IT), the resistivity variation in both the parallel and perpendicular directions had the characteristics of a relaxation as a function of temperature. During the IT the orientation of the PC microfibrils was gradually damaged and CNTs/PC microfibrils were deformed and changed to short fibers, leading to a transition from anisotropy to isotropy. The velocity of the conductive network reconstruction could be characterized by the relaxation time, and the resistivity of the composite during the IT process can be instantaneously predicted based on the relaxation equation. The relaxation time and the equilibrium resistivity of the composite during IT were determined by the IT temperature and CNT content. 相似文献
68.
Above Curie temperature, MnBi crystals are aligned in situ along the c-axis in a Bi matrix by a high fabrication magnetic field H f of 10 T. Magnetic testing shows a pronounced anisotropy in magnetization in directions normal and parallel to the fabrication field, resulting from the alignment. The successful alignment m v result from the fact that the easy magnetization direction is along the c-axis of MnBi and the high fabrication field of 10 T is large enough to rotate the )MnBi crystal to this direction even though the temperature is above the Curie temperature. 相似文献
69.
Ya-Hui Liu Wei Liu Zi-Li Zheng Xin Wei Nouman Ali Shah Hao Lin Bai-Song Zhao Shi-Shu Huang Jia-Zhuang Xu Zhong-Ming Li 《高分子科学》2021,39(9):1191-1199
Mimicking the complex structure of natural bone remains a challenge for bone tissue scaffolds.In this study,a novel processing strategy was developed to prepare the bone-like scaffolds that are featured by highly oriented and fully interconnected pores.This type of biomimetic scaffolds was evolved from solid phase stretching of immiscible polycaprolactone(PCL)/poly(ethylene oxide)(PEO)blends with co-continuous structure and the pore morphology was inherited from selective extraction of water soluble PEO phase.The pore anisotropy was readily tuned by varying the stretching strain without loss of interconnectivity.Significant promotion in preosteoblast proliferation,alkaline phosphatase activity and osteogenic gene expression was observed in the oriented porous scaffolds compared to the isotropic porous counterpart.The oriented architecture provided a topographical cue for aligned growth of preosteoblasts,which activated the Wnt/β-catenin signaling pathway.The proposed strategy enriches the toolbox for the scaffold design and fabrication for bone tissue engineering. 相似文献
70.
在水溶液中, 以乙烯基三乙氧基硅烷(VTES)为前驱体, 氨水(NH3 · H2O)为催化剂, 在表面活性剂十二烷基苯磺酸钠(SDBS)存在下, 通过溶胶-凝胶法成功合成了具有不同粒径、 高度单分散的聚乙烯基倍半硅氧烷(PVSQ)球形纳米粒子. 研究结果表明, 催化剂NH3 · H2O与表面活性剂SDBS的用量对PVSQ的粒径和粒径分布影响很大, 而前驱体VTES的用量对PVSQ的粒径无明显影响. 通过场发射扫描电子显微镜(FESEM)、 傅里叶变换红外光谱(FTIR)、 X射线光电子能谱(XPS)及热重(TG)分析对产物的形貌、 粒径和粒径分布、 结构及热性能进行了表征. 相似文献