Magnetization of finite carbon nanotubes

Magnetoelectronic properties of finite carbon nanotubes (CNs) are studied for an arbitrary field direction. They are strongly affected by the nanotube geometry (length, radius; boundary structure), the magnitude and direction of the magnetic field, the Zeeman effect, and the temperature. Geometric structures determine electronic structures and magnetic properties, which thus leads to three types of energy gaps and induced magnetic fields. The critical angle, which corresponds to the change of magnetism, exists in armchair CNs, but not in zigzag CNs. It also depends on the length and the radius of CNs. Finite CNs are very different from infinite CNs. Zeeman splitting could induce complete energy-gap modulation, a drastic change in magnetization, and a gigantic paramagnetic response for all zigzag CNs. The predicted results are observable even at room temperature.