Large Positive Magnetoconductance in Carbon Nanoscrolls.

We theoretically demonstrate that carbon nanoscrolls, spirally wrapped graphene layers with open end points, can be characterized by a large positive magnetoconductance. We show that when a carbon nanoscroll is subject to an axial magnetic field of several Tesla, the ballistic conductance at low carrier densities of the nanoscroll increases by about 200%. Importantly, we find that this positive magnetoconductance is not only preserved in an imperfect nanoscroll (with disorder or mild interturn misalignment) but can even be enhanced in the presence of on-site disorder. We prove that the positive magnetoconductance comes about with the emergence of magnetic-field-induced zero-energy modes, specific to rolled-up geometries. Our results establish curved graphene systems as a new material platform displaying sizable magnetoresistive phenomena.