Two-dimensional Josephson vortex lattice and anomalously slow decay of the Fraunhofer oscillations in a ballistic SNS junction with a warped Fermi surface

Article

关键词: EDGE;    SUPERCONDUCTIVITY;    NONLOCALITY;    COHERENCE;    VORTICES;    GRAPHENE;    STATE;   

DOI  :  10.1103/PhysRevB.94.094514

来源: SCIE

【 摘 要 】

The critical current of a Josephson junction is an oscillatory function of the enclosed magnetic flux Phi, because of quantum interference modulated with periodicity h/2e. We calculate these Fraunhofer oscillations in a two-dimensional (2D) ballistic superconductor-normal-metal-superconductor (SNS) junction. For a Fermi circle the amplitude of the oscillations decays as 1/Phi or faster. If the Fermi circle is strongly warped, as it is on a square lattice near the band center, we find that the amplitude decays slower, alpha 1/root Phi, when the magnetic length l(m) = root(h) over bar /eB drops below the separation L of the NS interfaces. The crossover to the slow decay of the critical current is accompanied by the appearance of a 2D array of current vortices and antivortices in the normal region, which form a bipartite rectangular lattice with lattice constant similar or equal to l(m)(2)/L. The 2D lattice vanishes for a circular Fermi surface, when only the usual single row of Josephson vortices remains.

【 授权许可】

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