Abnormal Magnetic Behaviors in Unique Square alpha-MnO2 Nanotubes
  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. 
R. Zeng, J. Q. Wang, W. X. Li, G. D. Du, Z. X. Chen, S. Li, S. X. Dou
cond-mat.mtrl-sci