共查询到18条相似文献,搜索用时 62 毫秒
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在转移矩阵方法及Mireles和Kirczenow的量子相干输运理论的基础上,研究了正常金属层/磁性半导体层/非磁绝缘层/磁性半导体层/正常金属层型双自旋过滤隧道结中Rashba自旋轨道耦合效应和自旋过滤效应对自旋相关输运的影响.讨论了隧穿磁电阻(TMR)、隧穿电导与各材料层厚度、Rashba自旋轨道耦合强度以及两磁性半导体中磁矩的相对夹角θ之间的关系.研究表明:含磁性半导体层的双自旋过滤隧道结由于磁性半导体层的自旋过滤效应和Rashba自旋轨道耦合作用可获得极大的TMR值.另外TMR和隧穿电导随着Rashba自旋轨道耦合强度的变化而振荡,振荡周期随Rashba自旋轨道耦合强度的增大逐渐减小.
关键词:
双自旋过滤隧道结
Rashba自旋轨道耦合
隧穿磁电阻
隧穿电导 相似文献
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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
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研究了两端具有铁磁接触的对称抛物势阱磁性隧道结(F/SPW/F)中自旋相关的隧穿概率和隧穿磁电阻,讨论了量子尺寸效应和Rashba 自旋轨道耦合作用对自旋极化输运特性的影响.研究结果表明:隧穿概率和隧穿磁电阻随抛物势阱宽度的增加发生周期性的振荡.抛物势阱深度的增加减小了隧穿概率和隧穿磁电阻的振荡频率.Rashba 自旋轨道耦合强度的增加加大了隧穿概率和隧穿磁电阻的振荡频率.隧穿概率和隧穿磁电阻的振幅和峰谷比强烈依赖于两铁磁电极中磁化方向的夹角.
关键词:
磁性隧道结
Rashba 自旋轨道耦合
隧穿概率
隧穿磁电阻 相似文献
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利用金属掩模法优化了制备磁性隧道结的实验和工艺条件,金属掩模的狭缝宽度为100 μm. 采用4 nm厚的Co75Fe25为铁磁电极和10或08 nm厚的铝氧化物 为势垒膜, 直接制备出了室温隧穿磁电阻(TMR)为30%—48%的磁性隧道结,其结构为Ta(5 nm)/Cu(25 nm)/Ni79Fe21(5 nm)/Ir22Mn78(10 nm)/ Co75Fe25 (4 nm)/Al(08 nm)-O/Co75Fe25(4 nm)/Ni79Fe 21(20 nm)/Ta(5 nm).同时,利用刻槽打孔法和去胶掀离法两种光刻技术并结合Ar离子束刻蚀及化学反应刻 蚀,制备出面积在4 μm×8 μm—20 μm×40 μm、具有室温高TMR和低电阻的高质量磁性 隧道结.300 ℃ 退火前后其室温TMR可分别达到22% 和50%.研究结果表明,采用光刻中的刻 槽打孔或去胶掀离工艺方法制备的小尺寸磁性隧道结,可用于研制磁动态随机存储器和磁读 出头及其他传感器件的磁敏单元.
关键词:
磁性隧道结
隧穿磁电阻
金属掩模法
光刻法 相似文献
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自旋输运和巨磁电阻--自旋电子学的物理基础之一 总被引:15,自引:1,他引:14
介绍磁性纳米结构和锰氧化物中电子的自旋极化输运和巨磁电阻效应,它们是新近发展的自旋电子学的物理基础之一.着重讨论的是以下三方面的基本物理图像:磁多层结构的巨磁电阻,铁磁隧道结的隧穿磁电阻,掺杂锰氧化物的庞磁电阻效应. 相似文献
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制备了Cu-Al2O3-MgF2-Au双势垒隧道发光结,分析了结加上一定偏压后的电子隧穿过程.指出由于构成隧道结的绝缘栅薄膜的厚度及禁带宽度的不同而导致双势垒中能级产生分裂,使电子通过栅区时产生共振隧穿现象.根据这一现象,并结合结的I-V特性,对结的发光性能进行了讨论.这种结构的结与普通单势垒MIM结相比,其发光效率(10-6—10-5)提高了近一个数量级,且发光光谱的波长范围及谱峰均向短波长方向
关键词: 相似文献
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We present first-principle calculations of electric and thermo spin transfer torques (STT) in Fe/Vacuum(Vac)/Fe magnetic tunnel junctions (MTJs). Our quantitative studies demonstrate rich bias dependence of STT and tunnel magneto resistance (TMR) behaviors with respect to the interface roughness. Thermoelectric effects in Fe/Vac/Fe MTJs is remarkable. We observe larger ZT of 6.2 in 8 ML clean Vacuum barrier, where the heavily restrained thermal conductance should be responsible for. Thermo-STT in Fe/Vac/Fe MTJs show same order as that in Fe/MgO/Fe MTJs with similar barrier thickness. 相似文献
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The effect of the ferromagnetic metal layer on tunnelling conductance and magnetoresistance in double magnetic planar junctions 下载免费PDF全文
Based on the free-electron approximation,we investigate the effect of the ferromagnetic metal layer on the tunnelling magnetoresistance(TMR) and tunnelling conductance(TC)in the double magnetic tunnel junctions(DMTJs) of the structure NM/FM/I(S)/NM/I(S)/FM/NM,where FM,NM and I(S) represent the ferromagnetic metal,nonmagetic metal and insulator(Semiconductor),respectively,The FM,I(S)and inner NM layers are of finite thickness,while the thickness of the outer NM layer is infinite.The calculated results show that,due to the spin-dependent interfacial potential barriers caused by electronic band mismatch between the various magnetic and nonmagnetic layers,the dependences of the TMR and TC on the thicknesses of the FM layers exhibit oscillations,and a much higher TMR can be obtained for suitable thicknesses of FM layers. 相似文献
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Thamrongsin Siripongsakul Andras Kovacs Amit Kohn Mikihiko Oogane Yasuo Ando 《哲学杂志》2016,96(4):310-319
The Co40Fe40B20(CFB)/MgO/CFB/MgO/CFB-based multilayer was prepared by conventional magnetron sputtering and utilised in the fabrication of double magnetic tunnel junctions (DMTJs) for which the middle CFB layers were island-shaped. By analysing the magnetic property of the CFB islands with Langevin’s equation, it was possible to identify their diameters of 7.6, 8.9 and 11.0 nm; accordingly submicron-scaled DMTJs were fabricated to investigate single-spin transport phenomena. The coulomb staircase and the oscillatory tunnel magnetoresistive (TMR) were able to be observed at 6 K, where the TMR ratio was enhanced up to 60%, which is the highest value ever achieved in this structure. 相似文献
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Perpendicular magnetic tunnel junction and its application in magnetic random access memory 下载免费PDF全文
Recent progresses in magnetic tunnel junctions with perpendicular magnetic anisotropy(PMA) are reviewed and summarized. At first, the concept and source of perpendicular magnetic anisotropy(PMA) are introduced. Next, a historical overview of PMA materials as magnetic electrodes, such as the RE–TM alloys TbFeCo and GdFeCo, novel tetragonal manganese alloys Mn–Ga, L10-ordered(Co, Fe)/Pt alloy, multilayer film [Co, Fe, CoFe/Pt, Pd, Ni, Au]N, and ultra-thin magnetic metal/oxidized barrier is offered. The other part of the article focuses on the optimization and fabrication of CoFeB/MgO/CoFeB p-MTJs, which is thought to have high potential to meet the main demands for non-volatile magnetic random access memory. 相似文献
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Dependences of spin polarization on the control parameters in the spin-polarized injection through the magnetic p-n junction 下载免费PDF全文
Effective spin-polarized injection from magnetic semiconductor (MS)
to nonmagnetic semiconductor (NMS) has been highlighted in recent
years. In this paper we study theoretically the dependence of
nonequilibrium spin polarization (NESP) in NMS during spin-polarized
injection through the magnetic p-n junction. Based on the theory in
semiconductor physics, a model is established and the boundary
conditions are determined in the case of no external spin-polarized
injection and low bias. The control parameters that may influence the
NESP in NMS are indicated by calculating the distribution of spin
polarization. They are the doping concentrations, the equilibrium
spin polarization in MS and the bias. The effective spin-polarized
injection can be realized more easily by optimizing the above
parameters. 相似文献
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《Current Applied Physics》2015,15(1):38-41
The crystallization characteristics of a middle CoFeB free layer in a magnetic tunnel junction (MTJ) with double MgO barriers were investigated by tunneling magnetoresistance (TMR) measurements of patterned cells across an 8-inch wafer. The MTJ structure was designed to have two CoFeB free layers and one bottom pinned layer, separated by MgO tunnel barriers. The observed resistance showed three types of TMR curves depending on the crystallization of the middle CoFeB layer. From the analysis of TMR curves, coherent crystallization of the middle CoFeB layer with the top and bottom MgO barriers was found to occur non-uniformly: About 80% of the MTJ cells in the wafer exhibited coherent crystallization of the middle CoFeB layers with the bottom MgO tunnel barrier, while others had coherent crystallization with the top MgO tunnel barrier or both barriers. This non-uniform crystallization of the middle CoFeB layer in a double MTJ was also clearly observed in tunneling electron microscopy images. Thus, control of the crystallization of the middle CoFeB layer is important for optimizing the MTJ with double MgO barriers, and especially for the fabrication of double barrier MTJ on a large area substrate. 相似文献
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Strain-mediated magnetoelectric control of tunneling magnetoresistance in magnetic tunneling junction/ferroelectric hybrid structures 下载免费PDF全文
Wenyu Huang 《中国物理 B》2022,31(9):97502-097502
Because of the wide selectivity of ferromagnetic and ferroelectric (FE) components, electric-field (E-field) control of magnetism via strain mediation can be easily realized through composite multiferroic heterostructures. Here, an MgO-based magnetic tunnel junction (MTJ) is chosen rationally as the ferromagnetic constitution and a high-activity (001)-Pb(Mg$_{1/3}$Nb$_{2/3}$)$_{0.7}$Ti$_{0.3}$O$_{3}$ (PMN-0.3PT) single crystal is selected as the FE component to create a multiferroic MTJ/FE hybrid structure. The shape of tunneling magnetoresistance (TMR) versus in situ E-fields imprints the butterfly loop of the piezo-strain of the FE without magnetic-field bias. The E-field-controlled change in the TMR ratio is up to $-$0.27% without magnetic-field bias. Moreover, when a typical magnetic field ($\sim \pm 10$ Oe) is applied along the minor axis of the MTJ, the butterfly loop is changed significantly by the E-fields relative to that without magnetic-field bias. This suggests that the E-field-controlled junction resistance is spin-dependent and correlated with magnetization switching in the free layer of the MTJ. In addition, based on such a multiferroic heterostructure, a strain-gauge factor up to approximately 40 is achieved, which decreases further with a sign change from positive to negative with increasing magnetic fields. This multiferroic hybrid structure is a promising avenue to control TMR through E-fields in low-power-consumption spintronic and straintronic devices at room temperature. 相似文献
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We investigate the electronic transport in a silicene-based ferromagnetic metal/ferromagnetic insulator/ferromagnetic metal tunnel junction. The results show that the valley and spin transports are strongly dependent on local application of a vertical electric field and effective magnetization configurations of the ferromagnetic layers. In particular, it is found that the fully valley and spin polarized currents can be realized by tuning the external electric field. Furthermore, we also demonstrate that the tunneling magnetoresistance ratio in such a full magnetic junction of silicene is very sensitive to the electric field modulation. 相似文献