  In laboratories, ultrahigh magnetic fields are usually produced with very
large currents through superconducting, resistive or hybrid magnets, which
require extreme conditions, such as low temperature, huge cooling water or tens
of megawatts of power. In this work we report that when single walled carbon
nanotubes (SWNTs) are cut, there are magnetic moments at the shearing end of
SWNTs. The average magnetic moment is found to be 41.5+-9.8uB per carbon atom
in the end states with a width of 1 nm at temperature of 300.0K, suggesting
ultrahigh magnetic fields can be produced. The dangling sigma and pi bonds of
the carbon atoms at the shearing ends play important roles for this
unexpectedly high magnetic moments because the oxidation temperature of cut
SWNTs is found to be as low as 312 in dry air. Producing ultrahigh magnetic
field with SWNTs has the advantage of working at higher working temperature and
with low energy consumption, suggesting great potentials of applications.
