Using first-principle methods, we investigate the magnetism properties of zigzag-edge graphene nanoribbons (ZGNRs) with a nanopore, and find that edges of such a nanopore show important effects although the electron transport is mainly along the outer edge of ZGNR. The robust bipolar spin semiconductor can be obtained when the edges of such a nanopore are varied, where both spin states have a gap but can relatively shift. We speculate that bipolar spin semiconductor behavior is related with two factors: broken inner edge states and width of electrode. A series of models are considered: 6-ZGNRs...
