Four-terminal impedance of a graphene nanoribbon based structure Yi-Jian Shi, Jin Lan, En-Jia Ye, Wen-Quan Sui and Xuean Zhao Eur. Phys. J. B, 87 10 (2014) 251 Published online: 27 October 2014 DOI: 10.1140/epjb/e2014-50321-0