Supercurrent flow through an effective double barrier structure

I. Zapata; F. Sols

doi:10.1103/PhysRevB.53.6693

paper

Supercurrent flow through an effective double barrier structure

arXiv:cond-mat/9511103 · doi:10.1103/PhysRevB.53.6693

Abstract

Supercurrent flow is studied in a structure that in the Ginzburg-Landau regime can be described in terms of an effective double barrier potential. In the limit of strongly reflecting barriers, the passage of Cooper pairs through such a structure may be viewed as a realization of resonant tunneling with a rigid wave function. For interbarrier distances smaller than $d_{0} = π ξ (T)$ no current-carrying solutions exist. For distances between $d_{0}$ and $2 d_{0}$ , four solutions exist. The two symmetric solutions obey a current-phase relation of $sin (Δ φ /2)$ , while the two asymmetric solutions satisfy $Δ φ = π$ for all allowed values of the current. As the distance exceeds $n d_{0}$ , a new group of four solutions appears, each contaning $(n - 1)$ soliton-type oscillations between the barriers. We prove the inexistence of a continuous crossover between the physical solutions of the nonlinear Ginzburg-Landau equation and those of the corresponding linearized Schrödinger equation. We also show that under certain conditions a repulsive delta function barrier may quantitatively describe a SNS structure. We are thus able to predict that the critical current of a SNSNS structure vanishes as $T_{c}^{'} - T$ , where $T_{c}^{'}$ is lower than the bulk critical temperature.

20 pages, RevTex, to appear in Phys. Rev. B, 6 figures on request at [email protected]

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SELFCONSISTENT CURRENT-VOLTAGE CHARACTERISTICS OF NORMAL-SUPERCONDUCTOR INTERFACES

Supercurrent flow through an effective double barrier structure

Abstract

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