• 文献标题:   Superconductivity-enhanced conductance fluctuations in few-layer graphene
  • 文献类型:   Article
  • 作  者:   TRBOVIC J, MINDER N, FREITAG F, SCHONENBERGER C
  • 作者关键词:  
  • 出版物名称:   NANOTECHNOLOGY
  • ISSN:   0957-4484
  • 通讯作者地址:   Univ Basel
  • 被引频次:   13
  • DOI:   10.1088/0957-4484/21/27/274005
  • 出版年:   2010

▎ 摘  要

We investigate the mesoscopic disorder induced rms conductance variance delta G in short few-layer graphene (FLG) flakes contacted by two superconducting (S) Ti/Al contacts. By sweeping the back-gate voltage, we observe pronounced conductance fluctuations superimposed on a linear background of the two-terminal conductance G. The linear gate voltage induced response can be modelled by a set of interlayer and intralayer capacitances. delta G depends on temperature T and source-drain voltage V-sd. delta G increases with decreasing T and |V-sd|. When lowering |V-sd|, a pronounced cross-over at a voltage corresponding to the superconducting energy gap Delta is observed. For |V-sd| less than or similar to Delta the fluctuations are markedly enhanced. Expressed in the conductance variance G(GS) of one graphene-superconductor (G-S) interface, values of 0.58e(2)/h are obtained at the base temperature of 230 mK. The conductance variance in the sub-gap region is larger by up to a factor of 1.4-1.8 compared to the normal state. The observed strong enhancement is due to phase coherent charge transfer caused by Andreev reflection at the G-S interface.