  In the resistive phase transition in VO2, temperature excursions from points
on the major hysteresis loop produce minor loops. We have found that for
sufficiently small excursions these minor loops degenerate into single-valued,
non-hysteretic branches (NHBs) having essentially the same or even higher
temperature coefficient of resistance (TCR) as the semiconducting phase at room
temperature. We explain this behavior and discuss the opportunities it presents
for infrared imaging technology based on resistive microbolometers. It is
possible to choose a NHB with 100 to 1000 times smaller resistivity than in a
pure semiconducting phase, thus providing a microbolometer with low tunable
resistivity and high TCR.
