In situ cleavage prepared bilayer graphene device and its large magnetoresistance Bo Zhao, Taishi Chen, Haiyang Pan and Peng Mao Eur. Phys. J. Appl. Phys., 72 2 (2015) 20401 Published online: 30 October 2015 DOI: 10.1051/epjap/2015150318