The Structure Of Superconductor / Normal Metal Hybrid Of Electronic Transport Properties In Graphene

In this paper, the transport properties of the graphene-based normal metal/superconductor hybrid structure (normal metal/superconductor/normal metal/superconductor/normal metal (NSNSN)) were studied. Because of the two superconducting layer in this structure, the effects of the superconducting phase and the energy gap on the transmission property were taken into account. The main results are summarized as follows:Using transfer-matrix method,we give the formulas of the transmission coefficient and conductivity of the NSNSN structure,the numrical results indicated that,the Fermi level,the width of the middle normal metal and the thickness of superconducting layer have a significant effect on the transmission coefficient in the case of certain condition.We first studied the angular-dependent transmission coefficient. The transmission coefficient is related to the Fermi level ( E F),the width of the middle normal metal layer (LN),the thickness of the first superconducting layer ( LS1 ). It is found that the transport properties of the structure are quite different from the other works.We also calculated the conductance with the variation of the width of the normal metal layer (LN). These results agree with those in an earlier work [C. Bai, Y. Yang and X. Zhang Appl. Phys. Lett. 92, 102513 (2008)]. It is also shown that the transport properties as a funtion of the thickness of the superconductor layer are totally different from that of the width of the normal metal layer.