Eur. Phys. J. B (2017) 90: 159
https://doi.org/10.1140/epjb/e2017-80226-1

Regular Article

Symmetry breaking effect on persistent current in graphene rings

¹ Department of Physics, Yancheng Institute of Technology, Yancheng 224051, P.R. China
² Department of Mechanical Engineering, University of Wisconsin Milwaukee, Milwaukee, WI 53211, USA
³ Department of Physics, Xiangtan University, Xiangtan 411105, P.R. China

^a e-mail: xuning79530@126.com

Received: 17 April 2017
Received in final form: 27 June 2017
Published online: 28 August 2017

Abstract

We calculate the electronic structure and persistent current of graphene rings based on tight binding theory. The sixfold rotational symmetrical graphene rings exhibit diamagnetic response with carriers flowing anticlockwise along the rings. When symmetry is broken by defect, these rings remain diamagnetic response. While for asymmetrical graphene ring with the same size, the typical current is several orders of magnitude smaller than that of sixfold rotational symmetrical graphene ring. Especially, the asymmetrical graphene rings exhibit not only diamagnetic but also paramagnetic response.