共查询到19条相似文献,搜索用时 171 毫秒
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环域结的位相差φ随时间演化的扰动Sine-Gordon方程(SGE)比in-line结的多出了与径向坐标ρ成反比的一项1/ρ (dφ)/(dρ),它的影响将随着ρ的减小而增大。我们的数值研究结果表明,不同的孤子行为出现在双孤子激发的状态:在内半径为7.5λ_J的环域结中,属于对称模式的双孤子激发只出现在低电流范围内,且在Ⅰ-Ⅴ曲线上呈现出迴滞现象;在内半径为50λ_J的环域结中,除了对称模式的激发外,还在高电流范围内出现串形模式的双孤子激发,在Ⅰ-Ⅴ曲线中也没有出现迴滞现象。 相似文献
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采用原子配位分布函数为Gaussian函数PG和指数函数PE直积的非 对称模型进行拟合计算,XAFS定量地研究化学还原法制备的Ni-P和Ni-Ce-P超细非晶合金大 无序度体系中Ni原子的局域环境结构随退火温度升高而产生的变化.结果表明Ni-P和Ni-Ce-P 原样的Ni-Ni配位的平均键长Rj、配位数N、热无序度σT、结构无 序度σS分别为0271nm,100,00060nm,0028n
关键词:
XAFS
Ni-P
Ni-Ce-P
超细非晶合金
局域结构 相似文献
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本文基于分子轨道法线性组合理论,推导出不同原子组成的分子的久期方程,从而得出分子波函数线性组合的特征常数N和λ的定量关系式,以及成键合能量和反键合能量的方程式.并通过这两能量之差,使N,λ系数与晶体对称势V共价所产生的平均能隙Eh,反对称蛰V离子所产生的能隙C和其总能隙Eg等相联系起来,导出了λ与分数光谱离子性fi和C/Eh比值间的关系式.由λ,N可导出fi与化合物半导体中离子射程参数间的关系式.应用上述一些关系式结合闪锌矿和纤锌矿结构特性,可以很好地解释两种结构的偏离系数γ(即化合物半导体中实际电子阻止本领对Bragg电子阻止本领的偏离系数)间互成倒数和压电系数epol的符号相反的原因.因此从C/Eh,γ,epol,对fi三曲线转折点完全一致,可以清晰地看出半导体化合物的价键和晶体结构特性决定了它的一系列物理、化学特性.
关键词: 相似文献
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孤子运动的Miles方程是一个具特征的非线性Schrdinger型方程.借求孤子解的微扰法,导出所遵循的矩阵方程,和孤子解的修正量δu(x,λ).并据双孤子解,计算了它的周期互作用状态
关键词:
Miles方程 微扰双孤子解 相似文献
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P. S. Lomdahl 《Journal of statistical physics》1985,39(5-6):551-561
The dynamics of the Josephson tunnel junction is approximately described by a perturbed sine-Gordon equation. The Josephson tunnel junction is thus a convenient experimental solid state device for the study of solitons and solitonlike phenomena. The physical manifestation of the soliton is a propagating magnetic flux quantum (
0=h/2e=2.064×10–15 V sec). Basic properties of the soliton and its relation to observable experimental quantities (zero field steps, microwave radiation, etc.) are reviewed. Recent direct measurements of the actual soliton profile are also mentioned. 相似文献
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It was experimentally evidenced, that Josephson radiation from an SNS junction exists, when a heat flow across the junction exceeds a critical value Pc. The ac component of the thermoelectric voltage was observed directly. The heat-flux-voltage characteristic of a TaCuTa junction showed steps of constant voltage, when the junction was irradiated by an external electromagnetic field at frequenct ~ 102 Hz. 相似文献
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RF responses of intrinsic Josephson junction stacks in the flux-flow state have been studied to explore vortex motion. We have reported various RF induced effects on flux-flow of Bi2Sr2CaCu2O8+y intrinsic Josephson junctions. In a pinning free state, a remarkable zero-crossing step appears at a certain voltage on I–V curve, which is closed to the voltage V = NΦ0f, where N is the number of junction, Φ0 is the flux quantum, f is the RF frequency, respectively. It is shown that vortex motion phase-locked to external microwaves play an important role in the responses. In this report, we have carried out numerical simulation by using the coupled sine-Gordon equations in order to compare with the experimental results. The numerical simulations reveal that the alternating magnetic field of microwaves drives vortices into the stack and generates the zero-crossing step. 相似文献
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现代可编程约瑟夫森电压基准的核心器件是约瑟夫森结阵.目前最具有优势的约瑟夫森结阵是 Nb/NbxSi1-x/Nb材料的结阵. Nb/NbxSi1-x/Nb材料的约瑟夫森结 具有三层薄膜的制作过程简便, Nb和NbxSi1-x刻蚀工艺相同以及NbxSi1-x 势垒层成分可调等优点.中国计量科学研究院设计制作了Nb/NbxSi1-x/Nb约瑟夫森单结. 通过在4.2 K低温下对所做单结进行直流电流-电压特性测量,观测到了清晰的超导隧穿电流和 从零电压态向电压态的跳变,最后就测量结果进行了分析讨论.此项工作属于国内首个开展 Nb/NbxSi1-x/Nb材料约瑟夫森单结研究的工作. 相似文献
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The Josephson junction containing localized magnetic moments in a dielectric layer between two superconductors is considered. Conditions are studied under which the phase difference between superconductors in the state with energy minimum is equal to π (such a junction we call π-junction). In addition we consider “one-dimensional” Josephson junction one part (2) of which is π-junction, the other (1) being the usual Josephson junction ( 0 - junction). Conditions are found under which in such a system there is a spontaneous vortex with the centre at the boundary between the parts 1 and 2 and magnetic flux associated with this vortex. The vortex appears by second order phase transition as temperature decreases for Tc. 相似文献
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M. Weides H. Kohlstedt R. Waser M. Kemmler J. Pfeiffer D. Koelle R. Kleiner E. Goldobin 《Applied Physics A: Materials Science & Processing》2007,89(3):613-617
We present a study on low-Tc superconductor-insulator-ferromagnet-superconductor (SIFS) Josephson junctions. SIFS junctions have gained considerable interest
in recent years because they show a number of interesting properties for future classical and quantum computing devices. We
optimized the fabrication process of these junctions to achieve a homogeneous current transport, ending up with high-quality
samples. Depending on the thickness of the ferromagnetic layer and on temperature, the SIFS junctions are in the ground state
with a phase drop of either 0 or π. By using a ferromagnetic layer with variable step-like thickness along the junction, we
obtained a so-called 0–π Josephson junction, in which 0 and π ground states compete with each other. At a certain temperature
the 0 and π parts of the junction are perfectly symmetric, i.e. the absolute critical current densities are equal. In this
case the degenerate ground state corresponds to a vortex of supercurrent circulating clock- or counterclockwise and creating
a magnetic flux which carries a fraction of the magnetic flux quantum Φ0.
PACS 74.50.+r; 74.78.Fk; 74.81.-g; 85.25.Cp 相似文献
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Current-voltage characteristics of the surface intrinsic Josephson junctions under a magnetic field parallel to CuO_2 planes have been studied experimentally. Fiske steps in such a junction have been observed. The Swihart velocity for the junction is found to be 7.2×10^5m/s, which corresponds to the velocity mode of a single junction. 相似文献