5.5: Theoretical hints of spin polarized electron field emission from carbon nanotubes

We study theoretically the spin polarized electron field emission from carbon nanotube (CN) within an axial magnetic field. It is found that the spin polarization of emission current can reach 0.05~0.08 with 0.1~1 μA emission current in the magnetic field 6 T and the electric field 9~12 V/nm at room temperature. The spin polarizations of the energy distributions oscillate and the peaks reach to 0.15~0.3 near Fermi energy in the magnetic field 6 T. In low temperature 50~100 K, the spin polarization of the emission current can reach to 0.1~0.2 with 0.01~0.02 μA emission current in the magnetic field 6 T and the electric field 8 V/nm. It decreases and remains 0.05 in the temperature ~400 K. These properties of the spin polarization in CN field emission originate from the modification of the energy band structure by the magnetic field.