共查询到19条相似文献,搜索用时 40 毫秒
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基于介观电路中电荷的量子化特性和介观电容中存在弱耦合效应的物理事实,对介观LC电路进行了量子力学处理,并讨论了电路中的类超导电流的量子特性。结果表明:无源情形时介观LC电路中类超导电流随时间变化具有周期性,其平均值为零;在直流稳压电源的作用下类超导电流存在直流分量,总电流平均值存在shapiro台阶;在交流电源的作用下类超导电流也可以存在直流分量,但总电流平均值不存在Shapiro台阶。 相似文献
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在临界温度Tc以下,超导体将磁通排出体外的现象被称为迈斯纳效应.对于第二类超导体,磁通可以部分地穿透,但总的来说,材料仍然是抗磁性的.然而,在高温超导(HTS)的研究中人们发现:某些高度无序的HTS材料对弱场表现出顺磁响应,这就是所谓顺磁迈斯纳效应(PME).对于PME,某些理论认为,它是源于HTS波函数的d波对称性.为了验证这类对称性,IBM华生研究中心的Kirtley等曾将各种HTS材料制成三晶介观环(直径~50μm),并测试其磁性.介观环的外延衬底是三晶SrTiO3晶体.每个三晶环均跨越衬… 相似文献
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Liang-Ma Shi Ren-Yi Zhu Shi-Ping Zhou 《Physica C: Superconductivity and its Applications》2011,471(11-12):373-377
Three-dimensional mesoscopic rings are investigated by the phenomenological Ginzburg–Landau theory in the presence of an externally applied magnetic-field. By solving an eigenvalue problem and minimizing systematic free energy, we find that the superconducting and normal states cyclically appear, and that between the state L and the state L + 1 the field extent of existing normal state increases with increase of vorticity L. The dimensional phase diagram with the maximum vorticity and existing normal state between two superconducting states is given. The normal state can be controlled by the medium with surface enhancement or suppression of superconductivity. 相似文献
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Polarized spin transport in mesoscopic quantum rings with electron--phonon and Rashba spin--orbit coupling 下载免费PDF全文
The influence of electron--phonon (EP) scattering on spin
polarization of current output from a mesoscopic ring with Rashba
spin--orbit (SO) interaction is numerically investigated. There are
three leads connecting to the ring at different positions;
unpolarized current is injected to one of them, and the other two
are output channels with different bias voltages. The spin
polarization of current in the outgoing leads shows oscillations as a
function of EP coupling strength owing to the quantum interference
of EP states in the ring region. As temperature increases, the
oscillations are evidently suppressed, implying decoherence of
the EP states. The simulation shows that the magnitude of polarized
current is sensitive to the location of the lead. The polarized
current depends on the connecting position of the lead in a
complicated way due to the spin-sensitive quantum interference
effects caused by different phases accumulated by transmitting
electrons with opposite spin states along different paths. 相似文献
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Spin-polarized transport through an Aharonov–Bohm (AB) semiconductor mesoscopic ring is investigated in the presence of both the Rashba spin–orbit interaction (RSOI) and the Dresselhaus spin–orbit interaction (DSOI). The ring symmetrically bridges two input and output electrodes. Based on tight-binding model and Green?s function formalism, we find that for AB fluxes other than integer or half-integer multiples of the flux quanta the ring acts as a spin selective device with unit efficiency only when the difference between strengths of RSOI and DSOI is nonzero and small. Results of this study can be used to design a nonmagnetic-material-based perfect spin filter. 相似文献
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基于紧束缚模型,考虑无序的梯度衰减,研究了无序-有序二维介观环体系中无序梯度及结构尺寸等因素对持续电流的影响.在表面无序区无梯度衰减时,持续电流随无序度的变化先减小后增大,观察到类弹道和局域性的转变.当存在梯度衰减时,无序区部分区域无序度相应减小,对有序区产生较强散射,典型电流比没有无序衰减时偏小.有趣的是,当无序度指数衰减时,上述类弹道和局域性的转变却消失了,揭示了介观实验中能否观察到该转变与无序的梯度分布密切相关.此外,计算表明表面无序渗透的深度和环的宽度对持续电流也有重要影响,呈现奇异的量子尺寸效应.这不同于以前的理论预言.
关键词:
介观环
梯度无序
持续电流 相似文献
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Guang-Yao HuangShi-Dong Liang 《Physics letters. A》2011,375(3):738-742
Novel quantum phases are found in the ground state of Rashba ring: the orbital magnetic phase (OMP), non-OMP, pseudo-OMP and quasi-OMP, which depend on the spin-orbit interaction (SOI) strength, electron number and ring size. We give the phase diagram and their quantum-phase-transition conditions. 相似文献
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M. Buballa 《Progress in Particle and Nuclear Physics》2008,61(1):66-72
The possible structure of the QCD phase diagram is discussed focusing on color superconducting quark matter in the region of low temperatures and moderately large densities, which could be relevant for compact stars. 相似文献