Simultaneously scanning two connected tips in a scanning tunneling microscope
Abstract
We have modified a dual-tip scanning tunneling microscope (STM) by electrically connecting the tips together with a short (3 mm) strip of flexible 25 mu m thick Nb foil. For simultaneous topographic imaging with both tips, we moved each tip to within tunneling distance z of a surface and modulated one tip s z-piezo at 5 kHz and the other at 10 kHz. The resulting combined tunneling current has modulation at both frequencies which we detect using individual lock-in amplifiers. Each lock-in output is fed back to its corresponding tip s individual STM z-position controller to maintain a stable current in both junctions. During the tests at room temperature, simultaneous imaging was performed with both tips made of Pt-Ir on Au/mica and highly oriented pyrolytic graphite (HOPG) samples, where a small tip-to-tip mechanical coupling was observed. We describe the system s performance, show results from simultaneous imaging, and discuss the potential application of the system to imaging superconducting phase differences. Published by AIP Publishing.
Publication Details
- Authors
- Publication Type
- Journal Article
- Year of Publication
- 2017
- Journal
- Journal of Applied Physics
- Volume
- 121