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1.
磁性隧道结材料中自旋相关的量子阱态所导致的共振隧穿现象具有很重要的研究和应用价值.文章介绍了最近在Fe(001)/MgO/Fe/MgO/Fe双势垒磁性隧道结中存在的量子阱共振隧穿效应的理论研究工作.通过量子阱态的第一性原理的计算以及结合对中间Fe薄膜孤岛结构所导致Coulomb阻塞效应的分析,证实了最近Nozaki等人(Nozaki T et al. Phys. Rev. Lett., 2006,96:027208 )实验中得到的振荡效应确实来源于中间Fe层多数自旋电子在Γ点处形成的Δ1对称性的量子阱态. 相似文献
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磁性隧道结材料中自旋相关的量子阱态所导致的共振隧穿现象具有很重要的研究和应用价值,文章介绍了最近在Fe(001)/MgO/Fe/MgO/Fe双势垒磁性隧道结中存在的量子阱共振隧穿效应的理论研究工作,通过量子阱态的第一性原理的计算以及结合对中间Fe薄膜孤岛结构所导致Coulomb阻塞效应的分析,证实了最近Nozaki等人(Nozaki T et al.Phys.Rev.Lett.,2006,96:027208)实验中得到的振荡效应确实来源于中间Fe层多数自旋电子在Г点处形成的△1对称性的量子阱态.Coulomb阻塞效应的存在正是导致实验中低温下量子阱共振隧穿效应不够明显的主要原因. 相似文献
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The conductive mechanisms of a titanium oxide memristor with dopant drift and a tunnel barrier 下载免费PDF全文
Nano-scale titanium oxide memristors exhibit complex conductive characteristics, which have already been proved by existing research. One possible reason for this is that more than one mechanism exists, and together they codetermine the conductive behaviors of the memristor. In this paper, we first analyze the theoretical base and conductive process of a memristor, and then propose a compatible circuit model to discuss and simulate the coexistence of the dopant drift and tunnel barrier-based mechanisms. Simulation results are given and compared with the published experimental data to prove the possibility of the coexistence. This work provides a practical model and some suggestions for studying the conductive mechanisms of memristors. 相似文献
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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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Vladislav S. Olkhovsky Vittoria Petrillo Jacek Jakiel Wiesław Kantor 《Central European Journal of Physics》2008,6(1):122-127
The particle tunneling through a 3-D rectangular potential barrier has been studied. The simplest model for multiple internal
reflections has been assumed. The explicit expression for all the transmission and reflection probability amplitudes have
been derived, as well as the tunneling and reflection phase times.
相似文献
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Characteristics of titanium oxide memristor with coexistence of dopant drift and a tunnel barrier 下载免费PDF全文
The recent published experimental data of titanium oxide memristor devices which are tested under the same experi- mental conditions exhibit the strange instability and complexity of these devices. Such undesired characteristics preclude the understanding of the device conductive processes and the memristor-based practical applications. The possibility of the coexistence of dopant drift and tunnel barrier conduction in a memristor provides preliminary explanations for the undesired characteristics. However, current research lacks detailed discussion about the coexistence case. In this paper, dopant drift and tunnel barrier-based theories are first analyzed for studying the relations between parameters and physical variables which affect characteristics of mernristors, and then the influences of each parameter change on the conductive behaviors in the single and coexistence cases of the two mechanisms are simulated and discussed respectively. The simulation results provide further explanations of the complex device conduction. Theoretical methods of eliminating or reducing the coex- istence of the two mechanisms are proposed, in order to increase the stability of the device conduction. This work also provides the support for optimizing the fabrications of memristor devices with excellent performance. 相似文献
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用Heaviside函数构造出一维对称的Hulthén势垒,求解了其满足的Klein-Gordon方程. 散射态的精确解可以由超几何函数表示, 透射系数T和反射系数R能由Klein-Gordon 方程满足的边界条件得到.并由流密度守恒推导出低动量粒子发生透射共振的条件.
关键词:
Klein-Gordon方程
Hulthén势垒
散射态
透射共振 相似文献
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H. M. Kim K. Kim S. J. Lee J. Joo H. S. Yoon S. J. Cho S. C. Lyu C. J. Lee 《Current Applied Physics》2004,4(6):577-580
We report charge transport properties such as d.c. conductivity (σDC) and its temperature dependence for composites of poly(methyl methacrylate) (PMMA) and multiwalled carbon nanotubes (MWCNTs). The MWCNTs were synthesized through chemical vapor deposition with Fe or Co as catalyst. The MWCNTs were homogeneously dispersed in PMMA matrix through sonication to prepare MWCNT–PMMA composite films. We controlled mass concentration of MWCNTs in the composites, and the thickness of MWCNT–PMMA composite films was 20–400 μm. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Raman spectroscopy were used to study structure and homogeneity of the composites. The σDC at room temperature of MWCNT–PMMA composites increased as mass concentration of MWCNTs increased, which followed percolation theory. Electromagnetic interference (EMI) shielding efficiency (SE) of MWCNT–PMMA composites was measured in the frequency range of 50 MHz–3.5 GHz. We observed the increase of EMI SE of MWCNT–PMMA composites with increasing the concentration of MWCNTs. 相似文献
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D. M. Sedrakian A. Zh. Khachatrian E. M. Kazaryan L. R. Sedrakian 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2009,44(3):113-119
We show that application of the immersing and transfer-matrix methods to one-dimensional problems of particles scattering leads to the system of two linear equations for the functions F and Φ expressed by means of the transmission and reflection amplitudes. The expressions of these functions are derived. The offered method is illustrated by the finding of transmission and reflection coefficients for the potential barrier with a constant height. The developed method can be applied in solving the quasi-one-dimensional and two-dimensional problems of scattering. 相似文献
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Lattice-controlled electron transport characteristics in quantized surface layers at low temperature
A theory of intravalley acoustic scattering of the carriers in a non-degenerate two-dimensional electron gas is developed here under the condition of low lattice temperature when the assumptions of the well-known traditional theory are not valid. The scattering rates thus obtained are then used to estimate the zero-field mobility characteristics in an n-channel Si inversion layer. It is found that the finite energy of the phonons makes the energy and lattice temperature dependence of the scattering rate, and consequently the lattice temperature dependence of the mobility, significantly different from what follows, in the light of traditional theory which assumes equipartition law for the phonon distribution and neglects the phonon energy in comparison to the carrier energy. 相似文献
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Influence of interface within the composite barrier on the tunneling electroresistance of ferroelectric tunnel junctions with symmetric electrodes 下载免费PDF全文
The interface with a pinned dipole within the composite barrier in a ferroelectric tunnel junction(FTJ) with symmetric electrodes is investigated.Different from the detrimental effect of the interface between the electrode and barrier in previous studies,the existence of an interface between the dielectric SrTiO3 slab and ferroelectric BaTiO3 slab in FTJs will enhance the tunneling electroresistance(TER) effect.Specifically,the interface with a lower dielectric constant and larger polarization pointing to the ferroelectric slab favors the increase of TER ratio.Therefore,interface control of high performance FTJ can be achieved. 相似文献
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B. Mukeru 《中国物理C(英文版)》2023,47(2):024104-024104-5
An analysis of the breakup of the \begin{document}$ ^{31}{\rm Ne} $\end{document} ![]()
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weakly-bound neutron-halo system on a lead target is presented, considering the \begin{document}$ 2p_{3/2} $\end{document} ![]()
![]()
and \begin{document}$ 1f_{7/2} $\end{document} ![]()
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ground-state configurations. It is shown that a high centrifugal barrier almost wipes out the breakup channel, thus assimilating the breakup of a weakly-bound system to that of a tightly-bound system, and also reduces the range of the monopole nuclear potential. Consequently, a high centrifugal barrier prevents the suppression of the Coulomb-nuclear interference (CNI) peak by weakening couplings to the breakup channel and reducing the range of the monopole nuclear potential, two main factors that would otherwise suppress such a peak. The present study also identifies couplings to the breakup channel and a long-ranged monopole nuclear potential as the main factors that lead to the suppression of the CNI peak. A low centrifugal barrier together with a Coulomb barrier would also effectively prevent the suppression of the CNI peak in proton-halos as reported in the case of the \begin{document}$ ^8{\rm B} $\end{document} ![]()
![]()
proton-halo. 相似文献
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利用递推格林函数技术计算了多终端量子体系的电子输运特性,首先运用递归方法给出介观 或量子体系的格林函数. 然后利用散射矩阵和输运方程给出体系的电导方程,可以将多终端 的输运简化为双终端的输运方程,以便得到体系电子输运的谱结构. 计算结果表明,由于中 间节点的存在,使器件的传输谱偏离一维链的对称性,在低能量端出现一个新的电导峰值. 此外,本方法可以被应用到各种复杂的带有吸附结构量子体系输运的研究中.
关键词:
格林函数
散射矩阵
量子体系 相似文献
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Spin-polarization-dependent transport in a quantum dot array coupled with an Aharonov-Bohm ring 下载免费PDF全文
In this paper the quantum transport in a dot-array coupled with an Aharonov–Bohm (AB) ring is investigated via single-band tight-binding Hamiltonian. It is shown that the output spin current is a periodic function of the magnetic flux in the quantum unit Φ0. The resonance positions of the total transmission probability do not depend on the size of the AB ring but the electronic spectrum. Moreover, the persistent currents in the AB ring is also spin-polarization dependent and different from the isolated AB ring where the persistent current is independent of spin polarization. 相似文献
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The polyethylene oxide (PEO) based lithium ion conducting polymer electrolytes complexed with lithium trifluoromethanesulfonate (LiCF3SO3 or LiTf) plasticized with an ionic liquid 1-ethyl 3-methyl imidazolium trifluoromethanesulfonate (EMITf) have been reported. Morphological, spectroscopic, thermal and electrochemical investigations demonstrate promising characteristics of the polymer films, suitable as electrolyte in various energy storage/conversion devices. Significant structural changes have been observed in the polymer electrolyte due to the ionic liquid addition, investigated by X-ray diffraction (XRD) and optical microscopy. The ion-polymer interaction, particularly the interaction of imidazolium cation with PEO chains, has been evidenced by IR and Raman spectroscopic studies. The optimized composition of the polymer electrolyte i.e. PEO25.LiTf + 40 wt.% EMITf offer room temperature ionic conductivity of ~ 3 × 10− 4 S cm− 1 with wide electrochemical stability window and excellent thermal stability. The ‘σ versus 1/T’ curves show apparent Arrhenius behavior below and above melting temperature. The ionic conductivity has been observed due to Li+ ions, as confirmed from 7Li-NMR studies, though the component ions of ionic liquid and anions also contribute significantly to the overall conductivity. 相似文献
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在氩气和空气混合气体介质阻挡放电中,研究了放电丝结构随外加电压及气体压强的变化,并从二维体系相变的角度进行了分析.随着电压的增加,放电丝结构的演变过程为:稀疏的随机放电丝—稠密的随机放电丝—六边形结构—超六边形结构—混沌态,此过程相应于二维体系的气相—液相—简单晶体—超点阵晶体—液相的相变过程.实验还研究了相变过程中超六边形形成中晶格常数及相邻格点间距离的变化、超六边形结构中大点的形成过程以及超六边形结构的Penta-Hepta缺陷. 相似文献
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在正常金属/绝缘层/s波超导隧道结(NIS结)中,以方势垒描述绝缘层对准粒子输运的影 响,运用Bogoliubov_de Gennes(BdG)方程、Blonder_Tinkham_Klapwijk(BTK)理论,计算 了NIS隧道结中的准粒子输运系数和微分电导.研究表明,微分电导随绝缘层厚度的变化呈振 荡和衰减两种趋势,其振荡的周期和衰减的快慢均强烈地依赖于绝缘层的势垒值以及V=Δ 0/e的偏压值,电导峰的高低及峰的位置与绝缘层厚度密切相关,显示了比δ势 描述更为丰富多彩的隧道谱.
关键词:
NIS结
方势垒
微分电导 相似文献