  We have developed a low-temperature scanning probe microscope using a quartz
tuning fork operating at 4.2 K. A silicon tip from a commercial cantilever was
attached to one prong of the tuning fork. With a metallic coating, a potential
could be applied to the tip to sense the charge distribution in a sample, while
with a magnetically coated tip, magnetic force imaging could be performed. For
the coarse approach mechanism, we developed a reliable low-temperature walker
with low material cost and simple machining. We have obtained Coulomb force
images of boron nanowires at room temperature and magnetic nano-structures at
low temperature. For lift-mode scanning, we employed a frequency detection mode
for the first topographic scan and phase detection mode for the second lift
scan.
