Supercurrent transferring through c-axis cuprate Josephson junctions with thick normal-metal-bridge

With simple but exactly solvable model, we investigate the supercurrent transferring through the c-axis cuprate superconductor-normal metal-superconductor junctions with the clean normal metal much thicker than its coherence length. It is shown that the supercurrent as a function of thickness of the normal metal decreases much slower than the exponential decaying expected by the proximity effect. The present result may account for the giant proximity effect observed in the c-axis cuprate SNS junctions.Comment: 6 pages, 4 figure

Classification of multipartite entanglement containing infinitely many kinds of states

We give a further investigation of the range criterion and Low-to-High Rank Generating Mode (LHRGM) introduced in \cite{Chen}, which can be used for the classification of $2\times{M}\times{N}$ states under reversible local filtering operations. By using of these techniques, we entirely classify the family of $2\times4\times4$ states, which actually contains infinitely many kinds of states. The classifications of true entanglement of $2\times(M+3)\times(2M+3)$ and $2\times(M+4)\times(2M+4)$ systems are briefly listed respectively.Comment: 11 pages, revte

Shubnikov de Haas effect in the metallic state of Na0.3_{0.3}CoO2_2

Shubnikov de Haas oscillations for two well defined frequencies, corresponding respectively to areas of 0.8 and 1.36% of the first Brillouin zone (FBZ), were observed in single crystals of Na$_{0.3}$CoO$_2$. The existence of Na superstructures in Na$_{0.3}$CoO$_2$, coupled with this observation, suggests the possibility that the periods are due to the reconstruction of the large Fermi surface around the $\Gamma$ point. An alternative interpretation in terms of the long sought-after $\epsilon_g^\prime$ pockets is also considered but found to be incompatible with existing specific heat data.Comment: 5 pages 4 figure

The `bare' strange stars might not be bare

It is proposed that the `bare' strange matter stars might not be bare, and radio pulsars might be in fact `bare' strange stars. As strange matter stars being intensely magnetized rotate, the induced unipolar electric fields would be large enough to construct magnetospheres. This situation is very similar to that discussed by many authors for rotating neutron stars. Also, the strange stars with accretion crusts in binaries could act as X-ray pulsars or X-ray bursters. There are some advantages if radio pulsars are `bare' strange stars.Comment: 11 pages, 1 Postscript figures, LaTeX, Chin. Phys. Lett. 1998, Vol.15, Nov.12, p.93

A Modeling Approach to Fiber Fracture in Melt Impregnation

© 2016, Springer Science+Business Media Dordrecht. The effect of process variables such as roving pulling speed, melt temperature and number of pins on the fiber fracture during the processing of thermoplastic based composites was investigated in this study. The melt impregnation was used in this process of continuous glass fiber reinforced thermoplastic composites. Previous investigators have suggested a variety of models for melt impregnation, while comparatively little effort has been spent on modeling the fiber fracture caused by the viscous resin. Herein, a mathematical model was developed for impregnation process to predict the fiber fracture rate and describe the experimental results with the Weibull intensity distribution function. The optimal parameters of this process were obtained by orthogonal experiment. The results suggest that the fiber fracture is caused by viscous shear stress on fiber bundle in melt impregnation mold when pulling the fiber bundle

Quasiparticle Scattering Interference in (K,Tl)FexSe2 Superconductors

We model the quasiparticle interference (QPI) pattern in the recently discovered (K,Tl)Fe_xSe2 superconductors. We show in the superconducting state that, due to the absence of hole pockets at the Brillouin zone center, the quasiparticle scattering occurs around the momentum transfer q=(0,0) and (\pm \pi, \pm \pi) between electron pockets located at the zone boundary. More importantly, although both d_{x^2-y^2}-wave and s-wave pairing symmetry lead to nodeless quasiparticle excitations, distinct QPI features are predicted between both types of pairing symmetry. In the presence of a nonmagnetic impurity scattering, the QPI exhibits strongest scattering with q=(\pm \pi, \pm \pi) for the d_{x^2-y^2}-wave pairing symmetry; while the strongest scattering exhibits a ring-like structure centered around both q=(0,0) and (\pm \pi, \pm \pi) for the isotropic s-wave pairing symmetry. A unique QPI pattern has also been predicted due to a local pair-potential-type impurity scattering. The significant contrast in the QPI pattern between the d_{x^2-y^2}-wave and the isotropic s-wave pairing symmetry can be used to probe the pairing symmetry within the Fourier-transform STM technique.Comment: 4+ pages, 3 embedded eps figure

Can Electric Field Induced Energy Gaps In Metallic Carbon Nanotubes?

The low-energy electronic structure of metallic single-walled carbon nanotube (SWNT) in an external electric field perpendicular to the tube axis is investigated. Based on tight-binding approximation, a field-induced energy gap is found in all (n, n) SWNTs, and the gap shows strong dependence on the electric field and the size of the tubes. We numerically find a universal scaling that the gap is a function of the electric field and the radius of SWNTs, and the results are testified by the second-order perturbation theory in weak field limit. Our calculation shows the field required to induce a 0.1 ${\rm eV}$ gap in metallic SWNTs can be easily reached under the current experimental conditions. It indicates a kind of possibility to apply nanotubes to electric signal-controlled nanoscale switching devices

Scaling and non-Abelian signature in fractional quantum Hall quasiparticle tunneling amplitude

We study the scaling behavior in the tunneling amplitude when quasiparticles tunnel along a straight path between the two edges of a fractional quantum Hall annulus. Such scaling behavior originates from the propagation and tunneling of charged quasielectrons and quasiholes in an effective field analysis. In the limit when the annulus deforms continuously into a quasi-one-dimensional ring, we conjecture the exact functional form of the tunneling amplitude for several cases, which reproduces the numerical results in finite systems exactly. The results for Abelian quasiparticle tunneling is consistent with the scaling anaysis; this allows for the extraction of the conformal dimensions of the quasiparticles. We analyze the scaling behavior of both Abelian and non-Abelian quasiparticles in the Read-Rezayi Z_k-parafermion states. Interestingly, the non-Abelian quasiparticle tunneling amplitudes exhibit nontrivial k-dependent corrections to the scaling exponent.Comment: 16 pages, 4 figure