A novel scanning tunnelling microscope head with a double-piezo-tube nested scanner for operation in a vibrational magnet.

Coarse stepping motor and imaging scanner are the most important components of the scanning tunnelling microscope (STM). In traditional STMs, a single small-sized piezoelectric tube is fixed directly to the motor and used as the imaging scanner, the small-sized scanner can only provide a small imaging area. As a result, those STMs need equipped with X-Y piezo stage to move sample. While the noise generated from coarse stepping motor and X-Y piezo stage, as well as the complex structure will greatly reduce the STM's imaging stability. In this paper, we present an independent scanner structure featuring a double-piezo-tube nested design. In this design, both two piezoelectric tubes can be responsible for adjusting the tip-sample distance; the external scan tube can be used to adjust the position of the sample. The small tip-sample mechanical loop and compact structure of the scanner ensure the high imaging stability of the new STM. Finally, we constructed a non-magnetic STM head based on above novel scanner. High-quality atomic images of the highly ordered pyrolytic graphite (HOPG) and low drift rates in both X-Y plane and Z directions were obtained at room temperature, demonstrating the high imaging stability of our new STM even at 300 K. Additionally, atomic images and the dI/dV spectra of NbSe2 obtained at 1.7 K, as well as the atomic images of HOPG obtained at changing magnetic fields from 0 T to 12 T in a vibrational magnet, proving new STM's high stability under low temperature and high magnetic fields.