Eur. Phys. J. B (2014) 87: 251
https://doi.org/10.1140/epjb/e2014-50321-0

Regular Article

Four-terminal impedance of a graphene nanoribbon based structure

¹ Zhejiang-California International Nanosystem Institute, Electronic Department, Zhejiang University, Hangzhou 310058, P.R. China
² School of Science, Jiangnan University, Wuxi 214122, P.R. China
³ Zhejiang Institute of Modern Physics, Zhejiang University, Hangzhou 310027, P.R. China

^a e-mail: hzzhaoxa@163.com

Received: 19 May 2014
Received in final form: 16 September 2014
Published online: 27 October 2014

Abstract

The four-terminal impedance is studied in a typical graphene nanoribbon based structure. When two additional voltage probes are attached, the results show that at the Dirac point, both the real and imaginary parts of the impedance are negative. As the Fermi energy deviates from the Dirac point, the real part of impedance oscillates with its sign changing frequently, while the imaginary part becomes vanishingly small. The phase incoherent processes introduced by the voltage probes contribute to inelastic scattering and charge redistribution in the central device region. As a result, the measured conductance is substantially different from the two-terminal measurement of a perfect graphene nanoribbon, indicating the important role of voltage probes in realistic four-terminal measurement.