  The transition voltage of an abrupt metal-insulator transition (MIT),
observed by applying an electric field to two-terminal devices fabricated on a
Mott insulator VO_2 film, decreases with increasing temperature up to 334K. The
abrupt current jump disappears above 334 K near the MIT temperature. These
results suggest that the mechanism of the abrupt MIT induced by temperature is
the same as that by an electric field. The magnitude of the current jump (a
large current) decreases with increasing external resistance; this is an
important observation in terms of applying the abrupt MIT to device
applications. Furthermore, the temperature and resistance dependence of the MIT
cannot be explained by the dielectric breakdown although a current jump known
as breakdown is similar to that observed in an abrupt MIT.
