Supercurrent

B. D. Josephson (Cambridge) theoretical predictions of the properties of a supercurrent through a tunnel barrier, in particular those phenomena which are generally known as the Josephson effects. 

Single or multifilament wire with a matrix of Cu or CuNi is commonly available in several diameters. Single-filament wire is usually reserved for low current applications. Multifilament wire has a higher critical current, since supercurrents flow only in the surfaces of superconductors, and in multifilamentary wire there is more superconducting surface. 

Paramagnetic supercurrents, 23 802-803 Paramagnetism, sodium, 22 761 Paramelaconite, 7 771 Parameter estimation, sampling techniques for, 26 1038-1939 Parameter optimization, 26 711 Paramyxoviruses, 3 137 Para-oriented polymers, 19 715 Paraquat, 13 315, 349 21 100, 120, 127 Para reds, 19 435 Parasites... 

Supercritical water reactions, 24 16-17 Supercurrents, diamagnetic and paramagnetic, 23 802-803 Superdex, 3 839 Superdislocation, 13 499 Superdispersants, 3 677 Superduplex stainless steels... 

E.A. Lynton, Superconductivity, Metheun, London, p. 23 (1969). Actually, all three fields (B, Hj, and M) are zero in the interior, but it is convenient to treat the superconductor as if it were a magnetic body where M is the equivalent magnetization produced by the screening supercurrents. 

But with the metal at a temperature below 7.2 K before the external field is removed, this current shows no sign of decay even when observations extend over a period of a year. As a result of such measurements, it has been estimated that it would require 10 years for the supercurrent to decay. Such persistent or frictionless currents in superconductors were observed in the early 1900s—hence they are not a recent discovery. 

The Josephson current, being an equilibrium supercurrent between two superconductors, can be calculated from the general thermodynamical relation... 

We have considered here the influence of dispersion asymmetry and Zee-man splitting on the Josephson current through a superconductor/quantum wire/superconductor junction. We showed that the violation of chiral symmetry in a quantum wire results in qualitatively new effects in a weak superconductivity. In particularly, the interplay of Zeeman and Rashba interactions induces a Josephson current through the hybrid ID structure even in the absence of any phase difference between the superconductors. At low temperatures (T critical Josephson current. For a transparent junction with small or moderate dispersion asymmetry (characterized by the dimensionless parameter Aa = (vif — v2f)/(vif + V2f)) it appears, as a function of the Zeeman splitting Az, abruptly at Az hvp/L. In a low transparency (D Josephson current at special (resonance) conditions is of the order of yfD. In zero magnetic field the anomalous supercurrent disappears (as it should) since the spin-orbit interaction itself respects T-symmetry. However, the influence of the spin-orbit interaction on the critical Josephson current through a quasi-ID structure is still anomalous. Contrary to what holds... 

All the phenomena described above are absent in a 2D-junction when the effects of transverse mode quantization are neglected [7]. We have considered the limiting case of a single (transverse) channel because this is the case when the effects induced by a dispersion asymmetry in the electron spectrum are most pronounced. The anomalous supercurrent Eq. (7) is a sign alternating function of the transverse channel index since for neighboring channels the spin projections of chiral states are opposite [4]. Besides, the absolute value of the dispersion asymmetry parameter decreases with transverse-channel number j. So, for a multichannel junction the effects related to a dispersion asymmetry phenomenon will be strongly suppressed and they completely disappear in the pure 2D case. 

In this section we calculate the Josephson current between the S layers of a FSFSF structure. We assume again that the thickness of the F layers dp is much larger than In this case the Josephson coupling between the S layers is due to the long range part of the TC. Therefore the supercurrent in the transverse direction is unusual, since it is caused by the triplet component of the condensate that is odd in frequency and even in momentum. 

We will see that the unusual character of the superconductivity in the transversal direction leads to peculiarities of the Josephson effect. For example, if the bias current flows through the terminal superconducting layer So and Sa (see Fig. 3), the supercurrent is zero because of the different symmetry of the condensate in So and Sa- In order to observe the Josephson effect in this structure the bias current has to pass through the layers Sa and Sb, as shown in Fig. 3. The supercurrent between S and S b is non-zero because each superconductor has its own TC and the phase difference tp is finite. 

Thus, if the condition dp is fulfilled the Josephson coupling between neighboring S layers is only due to the TC. Therefore in this case a new type of superconductivity may arise in the multilayered structures with non-collinear magnetizations. The supercurrent within each S layer is caused by the SC, whereas the supercurrent across the layers is caused by the triplet condensate, which is odd in the frequency iv and even in the momentum. 

Muller, C. J., van Ruitenbeek, X. M., and de Xongh, L. J., Conductance and supercurrent discontinuities in atomic-scale metallic constrictions of variable width. Phys. Rev. Lett. 69, 140... 

The internal supercurrent corresponding to operator (12) emerges, when the SC solution is modifi ed by adding an extra phase dhi, to pr) in the Bogoli-ubov transformation for b-states. If the phase 4>ab is the same for all stripe elements, then the translational supercurrent equals zero. However, when 4>ab has a weak position dependence, the zero-temperature density of translational supercurrent can be expressed as ... 

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