  We study the effciency of the magnetoimpedance (MI) of thin-wall
circumferentially ordered nanotubes in sub-GHz and GHz frequency regimes using
micromagnetic simulations. We consider empty ferromagnetic tubes as well as
tubes filled with non-magnetic conductors of circular cross-section (nanowire
coverings) focusing on the low-field regime of MI (below the characteristic
field of the low-frequency ferromagnetic resonance). In this field area, the
effcient mechanism of MI is related to oscillations of the positions of
(perpendicular to the tube axis) domain walls (DWs). Two mechanisms of driving
the DW motion by the ac current are taken into account; the driving via the
Oersted field and via the spintransfer torque. The simulations are performed
for Co nanotubes of the diameter of 300nm. Achievable low-field MI exceeds
100%, while the field region of a high sensitivity of that DW-based giant MI is
of the width of tens of kA/m. The later is widely adjustable with changing the
density of the driving ac current, its frequency, and the nanotube length. Of
particular interest is the resonant motion of DW due to the interaction with
the nanotube ends the conditions of whom are discussed.
