Pseudodiffusive conduction at the Dirac point of a normal-superconductor junction in graphene

被引:31
作者
Akhmerov, A. R. [1 ]
Beenakker, C. W. J. [1 ]
机构
[1] Leiden Univ, Inst Lorentz, NL-2300 RA Leiden, Netherlands
来源
PHYSICAL REVIEW B | 2007年 / 75卷 / 04期
关键词
D O I
10.1103/PhysRevB.75.045426
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
A ballistic strip of graphene (width W > length L) connecting two normal metal contacts is known to have a minimum conductivity of 4e(2)/pi h at the Dirac point of charge neutrality. We calculate what happens if one of the two contacts becomes superconducting. While the ballistic conductance away from the Dirac point is increased by Andreev reflection at the normal-superconductor (NS) interface, we find that the minimum conductivity stays the same. This is explained as a manifestation of pseudodiffusive conduction at the Dirac point. As a generalization of our results for a ballistic system, we provide a relation between the conductance G(NS) of an arbitrarily disordered normal-superconductor junction in graphene and its value G(N) when both contacts are in the normal state.
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页数:4
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