Control Of Atomic Force Microscope Research Articles

Scattering-type scanning near-field optical microscopy with Akiyama piezo-probes

Recent developments of the scattering-type scanning near-field optical microscope at cryogenic temperatures (cryogenic s-SNOM or cryo-SNOM) have led to many breakthroughs in the studies of low energy excitations in quantum materials. However, the simultaneous demands on vibration isolation, low base temperature, precise nano-positioning, and optical access make the construction of a cryo-SNOM a daunting task. Adding to the overhead space required for a cryo-SNOM is the atomic force microscopy control, which predominantly utilizes a laser-based detection scheme for determining the cantilever tapping motion. In this work, we provide an alternative and straightforward route to performing s-SNOM using metal-coated Akiyama probes, where the cantilever tapping motion is detected through a piezoelectric signal. We show that the Akiyama-based cryo-SNOM attains high spatial resolution, good near-field contrast, and is able to perform imaging with a significantly more compact system compared to other cryo-SNOM implementations. Our results firmly establish the potential of s-SNOM based on self-sensing piezo-probes, which can easily accommodate far-infrared wavelengths and high magnetic fields in the future.

New technique for nanocantilever fabrication based on local electrochemical etching: Applications to scanning force microscopy

We propose a new method to fabricate a nanocantilever with a mechanical oscillating ball on its end. The method is based on local electrochemical etching in a very thin electrolyte liquid layer. It allows fabrication of a very sharp tip as well as a ball tip that can be used in dynamic mode control of atomic force microscopy. The oscillating part measures 50 nm in diameter; the diameter of the ball tip is 1.5 μm. Because of the small mass of the oscillating ball and the small size of the threadlike neck, the estimated resonance frequency is around 300 MHz. This technique will help to increase the force gradient sensitivity in dynamic mode control of atomic force microscopy.