Josephson effect in mesoscopic graphene strips with finite width

Ali G. Moghaddam; Malek Zareyan

doi:10.1103/PhysRevB.74.241403

paper

Josephson effect in mesoscopic graphene strips with finite width

arXiv:cond-mat/0611577 · doi:10.1103/PhysRevB.74.241403

Abstract

We study Josephson effect in a ballistic graphene strip of length $L$ smaller than the superconducting coherence length and arbitrary width $W$ . We find that the dependence of the critical supercurrent $I_{c}$ on $W$ is drastically different for different types of the edges. For \textit{smooth} and \textit{armchair} edges at low concentration of the carriers $I_{c}$ decreases monotonically with decreasing $W / L$ and tends to a constant minimum for a narrow strip $W / L ≲ 1$ . The minimum supercurrent is zero for smooth edges but has a finite value $e Δ_{0} /ℏ$ for the armchair edges. At higher concentration of the carriers, in addition to this overall monotonic variation, the critical current undergoes a series of peaks with varying $W$ . On the other hand in a strip with \textit{zigzag} edges the supercurrent is half-integer quantized to $(n + 1/2) 4 e Δ_{0} /ℏ$ , showing a step-wise variation with $W$ .

4 pages, 3 figures

Josephson effect in mesoscopic graphene strips with finite width

Abstract

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