  We demonstrate theoretically that an array of carbon nanoscrolls acts as a
hyperbolic magnetic metamaterial in the THz regime with genuine subwavelength
operation corresponding to wavelength-to-structure ratio of about 200. Due to
the low sheet resistance of graphene, the electromagnetic losses in an array of
carbon nanoscrolls are almost negligible offering a very sharp magnetic
resonance of extreme positive and negative values of the effective magnetic
permeability. The latter property leads to superior imaging properties for
arrays of carbon nanoscrolls which can operate as magnetic endoscopes in the
THz where magnetic materials are scarce. Our optical modelling is supplemented
with ab initio density-functional calculations of the self-winding of a single
layer of graphene onto a carbon nanotube so as to form a carbon nanoscroll. The
latter process is viewed as a means to realize ordered arrays of carbon
nanoscrolls in the laboratory based on arrays of aligned carbon nanotubes which
are nowadays routinely fabricated.
