▎ 摘　　要

Folded graphene nanoribbons were observed and their unusual transport properties were reported recently. In this work, the electronic structures and the effects of external transverse electrical field in the folded zigzag-edged graphene nanoribbons (ZGNRs) are investigated by first-principles calculations. It is found that, the folding does not break the semiconductivity, the antiferromagnetically coupled edge states and edge magnetism characteristic of ZGNRs. Interestingly, when external electrical field is applied, the ribbons can be turned to metal or half-metal, depending on the direction of the field. The robustness of the half-metallicity and the edge magnetism to the electrical field is also discussed. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3504259]