Superconductivity-enhanced conductance fluctuations in few-layer graphene

Trbovic, J. and Minder, N. and Freitag, F. and Schonenberger, C.. (2010) Superconductivity-enhanced conductance fluctuations in few-layer graphene. Nanotechnology, Vol. 21, H. 27 , 274005.

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Official URL: http://edoc.unibas.ch/dok/A6070313

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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.
Faculties and Departments:05 Faculty of Science > Departement Physik > Physik > Experimentalphysik Nanoelektronik (Schönenberger)
UniBasel Contributors:Schönenberger, Christian and Freitag, Frank and Trbovic, Jelena
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:IOP Publ.
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:08 Oct 2021 03:10
Deposited On:01 Feb 2013 08:44

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