For the first time positive piezoconductive effect is observed in suspended bi- and multi- layer graphene, which can be understood as resulting from the strain-induced competition between interlayer coupling and intralayer transport. The paper, entitled the positive piezoconductive effect in graphene, was published on Sep. 11 in Nature Communications as an online paper.
Graphene, an allotrope of carbon in a two-dimensional atomic-scale form, was first produced and isolated by Geim and Novoselov in 2004 and opened the era of 2-dimensional material study. Due to a number of advantageous features such as unparalleled breaking strength and excellent controllability of electronic structures via mechanical strain, Graphene has attracted much attention ever since. Many intriguing phenomena have been experimentally observed on strained graphene, including the observation of pseudo-magnetic fields exceeding 300 T. And even more fascinating phenomena have been theoretically predicted but yet to be realized experimentally, for example the zero-field quantum Hall effect and strain-induced superconductivity of graphene.
Fig:The positive piezoconductive effect was observed in graphene and the underlying mechanism was decoded by Chinese researchers./Copyright by QIAO's Group
As with the correlations between electrical properties and mechanical strains, early studies have focused on the negative piezoconductive effect on mono-layer graphene. Researchers explored the potential roles of layer number and interlayer interactions and observed dinsdinct positive piezoconductance in bi- and multi-layer graphene. The negative piezoconductance can be explained in terms of strain-induced decrease of Fermi velocity, while the positive piezoconductive effect, according to them, can be interpreted by the model of strain-induced competition between electronic interlayer coupling and intralayer transport. The study enrichs the understanding of electromechanical properties of graphene and contributes to their potential applications in nano-electromechanical systems and flexible electronics fields.
This study was lead by Professor QIAO Zhenhua from Hefei National Laboratory for Physical Sciences at the Microscale (HFNL) and School of Physics, and Prof. MIAO Feng from Nanjing University. PhD candidate WANG Ke from QIAO group served as the co-first auther of this paper.
This research was supported by the China National Science Foundation, Chinese Academy of Sciences Hundred Talent Program, Thousand Talent Program for Young Outstanding Scientists, Ministry of Education Project 2011, Anhui Provincial Natural Science Foundation Grants. Supercomputing center of USTC also gave crucial support to the study.
Prof. QIAO Zhenhua
Email: qiao@ustc.edu.cn
Phone number: 0551-63607539
Homepage: http://staff.ustc.edu.cn/~qiao/
Original paper: www.nature.com/ncomms/2015/150911/ncomms9119/full/ncomms9119.html
(LI Xiaorun, USTC News Center)