A low temperature scanning probe microscope using a quartz tuning fork

A frequency modulation-atomic force microscope (FM-AFM) designed to measure atomic scale topography at low temperatures is developed. Piezoelectric quartz tuning forks are employed as a force sensor for low temperatures use. In order to perform high-resolution measurements, detection of attractive forces between a tip and a sample is important. Measurements of attractive van der Waals forces on a SrTiO₃ substrate is successfully performed down to 4.2 K by minimizing an amplitude of the tuning fork. Topographic imaging of atomic steps of the SrTiO₃ substrate is also achieved at room temperatures in vacuum (10^-3 Pa).