Enhancement of subgap conductance in a graphene superconductor junction by valley polarization

We theoretically study the differential conductance of a graphene/graphene superconductor junction, where the valley polarization of Dirac electrons is considered in the nonsuperconducting region. It is shown that the subgap conductance will increase monotonically with the valley-polarization streng...

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Bibliographic Details
Published in:Chinese physics B 2017-02, Vol.26 (2), p.428-434
Main Author: 李传新 汪萨克 汪军
Format: Article
Language:English
Subjects:
单调增加
单调递减
回归反射
微分电导
极化强度
狄拉克
石墨
超导结
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Summary:We theoretically study the differential conductance of a graphene/graphene superconductor junction, where the valley polarization of Dirac electrons is considered in the nonsuperconducting region. It is shown that the subgap conductance will increase monotonically with the valley-polarization strength when the chemical potential μ is near the Dirac point μ≤ 3？（？ is the superconducting gap）, whereas it will decrease monotonically when μ is far away from the Dirac point, μ≥ 5？.The former case is induced by the specular Andreev reflection while the retro-reflection accounts for the later result. Our findings may shed light on the control of conductance of a graphene superconductor junction by valley polarization.
ISSN:1674-1056
2058-3834
DOI:10.1088/1674-1056/26/2/027304