直流和交流Josephson效应的研究

基于Feynman模型得到的Josephson方程,在求解过程中采取了ρ1=ρ2的假设,但这个假设在数学处理上并不严格。为了得到严格的结果,未进行上述假设,通过解微分方程得到了严格的Josephson方程,结果显示在一定条件下才能得到通常所说的Josephson方程。     

Dynamics in coupled oscillators with recurrent/random forcing, a PDE approach

The current paper is devoted to the study of coupled oscillators with recurrent/random forcing. Special attention is given to the solutions having the same recurrence/randomness as that of the forcing (recurrent/random solutions for short). By embedding coupled oscillators into coupled parabolic equations, it establishes a general theorem on the existence of recurrent/random solutions. It also finds conditions under which such solutions are unique. When the recurrent forcing is actually quasi-periodic or almost periodic, recurrent solutions are refereed to as quasi-periodic or almost periodic solutions in a weak sense and they are quasi-periodic or almost periodic in the classical sense under the uniqueness conditions. In addition, applications of the general theory to coupled Duffing type oscillators and Josephson junctions are considered and the results obtained extend several existing ones for quasi-periodic Duffing oscillators.     

Finite-size-scaling analyses of the chiral ordert in the Josephson-junction ladder with half a flux quantum per plaquette

Chiral order of the Josephson-junction ladder with half a flux quantum per plaquette is studied by means of the exact diagonalization method. We consider an extreme quantum limit where each superconductor grain (order parameter) is represented by S=1/2 spin. So far, the semi-classical case, where each spin reduces to a plane rotator, has been considered extensively. We found that in the case of S=1/2, owing to the strong quantum fluctuations, the chiral (vortex lattice) order becomes dissolved except in a region, where attractive intrachain and, to our surprise, repulsive interchain interactions both exist. On the contrary, for considerably wide range of parameters, the superconductor (XY) order is kept critical. The present results are regarded as a demonstration of the critical phase accompanying chiral-symmetry breaking predicted for frustrated XXZ chain field-theoretically. Received 20 February 2000     

The Effect of Triple Junctions on Grain Boundary Motion and Grain Microstructure Evolution

The theory of steady state motion of grain boundary sytems with triple junctions and the main features of such systems are considered. A special technique of in-situ observations and recording of triple junction motion is introduced, and the results of experimental measurements on Zn tricrystals are discussed. It is shown, in particular, that the described method makes it possible to measure the triple junction mobility. It was found that the measured shape of a moving half-loop with a triple junction agrees with theoretical predictions. A transition from triple junction kinetics to grain boundary kinetics was observed. This means that triple junctions can drag boundary motion. It is demonstrated that the microstructural (granular) evolution is slowed down by triple junction drag for any n-sided grain. The second consequence pertains to six-sided grains. For a boundary system with dragging triple junctions there is no unique dividing line between vanishing and growing grains with respect to their topological class anymore, like n = 6 in the Von Neumann-Mullins relation.     

有限温度下介观L-C电路数-相量子涨落

借助于Weyl量子化方案,我们用数-相量子化观点讨论了有限温度下L-C回路的量子噪声,给出了噪声与温度T的函数关系,从数-相量子化方案还能给出相算符的具体形式及电路的振荡行为。     

异种金属焊接接头的电子探针分析

用电子探针对异种金属摩擦焊接接头进行了扩散组元含量分布和成分定量分析。结果表明电子探针能有效地分析出固体中的微观传质现象,同时可方便地测出接头处扩散层的宽度和微观组织结构变化情况。     

Photoresponsive Molecular Memory Films Composed of Sequentially Assembled Heterolayers Containing Ruthenium Complexes

Photoresponsive molecular memory films were fabricated by a layer‐by‐layer (LbL) assembling of two dinuclear Ru complexes with tetrapodal phosphonate anchors, containing either 2,3,5,6‐tetra(2‐pyridyl)pyrazine or 1,2,4,5‐tetra(2‐pyridyl)benzene as a bridging ligand (Ru‐NP and Ru‐CP, respectively), using zirconium phosphonate to link the layers. Various types of multilayer homo‐ and heterostructures were constructed. In the multilayer heterofilms such as ITO||(Ru‐NP)_m|(Ru‐CP)_n, the difference in redox potentials between Ru‐NP and Ru‐CP layers was approximately 0.7 V, which induced a potential gradient determined by the sequence of the layers. In the ITO||(Ru‐NP)_m|(Ru‐CP)_n multilayer heterofilms, the direct electron transfer (ET) from the outer Ru‐CP layers to the ITO were observed to be blocked for m>2, and charge trapping in the outer Ru‐CP layers became evident from the appearance of an intervalence charge transfer (IVCT) band at 1140 nm from the formation of the mixed‐valent state of Ru‐CP units, resulting from the reductive ET mediation of the inner Ru‐NP layers. Therefore, the charging/discharging (“1”and “0”) states in the outer Ru‐CP layers could be addressed and interconverted by applying potential pulses between ?0.5 and +0.7 V. The two states could be read out by the direction of the photocurrent (anodic or cathodic). The molecular heterolayer films thus represent a typical example of a photoresponsive memory device; that is, the writing process may be achieved by the applied potential (?0.5 or +0.7 V), while the readout process is achieved by measuring the direction of the photocurrent (anodic or cathodic). Sequence‐sensitive multilayer heterofilms, using redox‐active complexes as building blocks, thus demonstrate great potential for the design of molecular functional devices.