  Systematic magnetic measurements have been performed in unique$\alpha -
MnO_2$ square nanotubes synthesized by a facile hydrothermal method with
microwave-assisted procedures. Unusual magnetic phenomena (abnormal
magnetization verse temperature (M - T) behaviour, large and abnormal
magnetization hysteresis loop horizontal shift (HHS) verse cooling field (HFC)
behaviours (HHS - HFC) has been observed in these square nanotubes. These
suggest the observation of large unfrozen orbital moment which also is the
micro -original of observed large and abnormal horizontal shift (HHS). The
findings demonstrated that engineering layered structures in nanoscale would
create many unique nanostructures and unusual physicochemical behaviours.
