Subgap anomaly and above-energy-gap structure in chains of diffusive SNS junctions

We review and refine analytical results on the density of states in a long disordered superconductor - normal-metal - superconductor junction with transparent interfaces. Our analysis includes the behavior of the minigap near phase differences zero and PI across the junction, as well as the density of states at energies much larger than the minigap but much smaller than the superconducting gap.

We express the low-frequency shot noise in a disordered normal-metal - superconductor (NS) junction at finite (subgap) voltage in terms of the normal scattering amplitudes and the Andreev reflection amplitude. In the multichannel limit, the conductance exhibits resonances which are accompanied by an enhancement of the (differential) shot noise. In the study of multichannel single and double barrier junctions we discuss the noise properties of coherent transport at low versus ...

The paper develops the theory of the ballistic SNS sandwich, in which the Josephson effect exists without the proximity effect. The theory takes into account restrictions imposed by the charge conservation law and the incommensurability of the superconducting gap with the Andreev level energy spacing. This resulted in revisions of some conclusions of previous works. In the one-dimensional case the Josephson phase of the ground state of the ballistic SNS sandwich is not necess...

In this work, we briefly overview various options for Josephson junctions which should be scalable down to nanometer range for utilization in nanoscale digital superconducting technology. Such junctions should possess high values of critical current, $I_c$, and normal state resistance, $R_n$. Another requirement is the high reproducibility of the junction parameters across a wafer in a fabrication process. We argue that Superconductor - Normal metal - Superconductor (SN-N-NS)...

We study low temperature electron transport in p-wave superconductor-insulator-normal metal junctions. In diffusive metals the p-wave component of the order parameter decays exponentially at distances larger than the mean free path $l$. At the superconductor-normal metal boundary, due to spin-orbit interaction, there is a triplet to singlet conversion of the superconducting order parameter. The singlet component survives at distances much larger than $l$ from the boundary. It...

When two fully polarized ferromagnetic (F) wires with opposite polarizations make contact with a spin-singlet superconductor, a potential-induced current in wire 1 induces a non-local current of equal magnitude and sign in wire 2. The magnitude of this current has been studied in the tunneling limit and found to decay exponentially with the distance between the contact. In this paper we propose a new structure in which this novel non-local effect is increased by orders of mag...

We study the transport properties of a NSN structure with an insulating barrier at each NS interface. Coherent quasiparticle scattering is assumed and self-consistency is implemented exactly to guarantee local charge conservation. The presence of a finite condensate flow has a greater influence on the transport properties than either the gap depression near the interfaces or the coherent nature of scattering. We find that a nonzero phase gradient causes a shift towards lower ...

In this paper we address several new developments in the theory of dc Josephson effect in superconducting weak links. We analyze an interplay between quantum interference effects and Andreev reflection in SNS nanojunctions with insulating barriers and demonstrate that such effects may qualitatively modify the Josephson current in such structures. We also investigate an impact of the parity effect on persistent currents in superconducting nanorings interrupted by a quantum poi...

We investigate heat and charge transport in NN'IS tunnel junctions in the diffusive limit. Here N and S are massive normal and superconducting electrodes (reservoirs), N' is a normal metal strip, and I is an insulator. The flow of electric current in such structures at subgap bias is accompanied by heat transfer from the normal metal into the superconductor, which enables refrigeration of electrons in the normal metal. We show that the two-particle current due to Andreev refl...

The analysis in the present paper is based on the most known concept introduced by the brilliant physicist Alexander Andreev: Andreev bound states in a normal metal sandwiched between two superconductors. The paper presents results of direct calculations of {\em ab initio} expressions for the currents in a long ballistic SNS junction. The expressions are expanded in $1/L$ ($L$ is the thickness of the normal layer). The main contribution $\propto 1/L$ to the current agrees wit...