Supercurrent flow through an effective double-barrier structure

Article

关键词: NORMAL METAL;   

DOI  :  10.1103/PhysRevB.53.6693

来源: SCIE

【 摘 要 】

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) = pi xi(T) no current-carrying solutions exist. For distances between d(0) and 2d(0), four solutions exist. The two symmetric solutions obey a current-phase relation of sin(Delta phi/2), while the two asymmetric solutions satisfy Delta phi = pi for all allowed values of the current. As the distance exceeds nd(0), a group of four solutions appears, each containing (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 Schrodinger equation. We also show that under certain conditions a repulsive delta function barrier may quantitatively describe a superconductor-normal-superconductor (SNS) structure. We conclude that the critical current of a SNSNS structure vanishes as root T'(c)-T, where T'(c) is lower than the bulk critical temperature.

【 授权许可】

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